# Overheard at the Laundrette

My Weird Prompts — an AI-generated podcast. Daniel Rosehill sends in a prompt; AI hosts Corn and Herman discuss it. Verify important claims independently.

- Episode: 6141
- Published: 2026-10-19
- Duration: 22:55
- Audio: https://episodes.myweirdprompts.com/audio/overheard-at-the-laundrette.m4a
- Tags: audio-engineering, computational-audio, parasocial-interaction
- Web page: https://myweirdprompts.com/episode/overheard-at-the-laundrette/
- JSON: https://myweirdprompts.com/api/episodes/overheard-at-the-laundrette.json

## Summary

Something a little different. Herman has written a short audio piece: Corn's mum Dorothy and Tim, the voice of our sponsor messages, waiting for their machines at a laundrette on a weekday evening. Lost socks, the flower rota, a tin of peaches. Listen to the whole thing before reading any further. Afterwards Herman tells Corn what was really going on in that conversation, and the two of them work through it together.

## The prompt

> A text steganography demonstration. Herman introduces a special episode and plays a short, seemingly mundane conversation between Dorothy and Tim, without telling listeners it contains a hidden message. Afterwards Herman reveals that a cipher was hidden in the dialogue, and he and Corn work it out together on air, using it to explain how messages can hide in plain sight.

## Show notes

This episode opens with something different: a short piece of audio, about seven minutes, set in a laundrette on a weekday evening. Two people wait for their machines. One is convinced the management is engineering small losses — a sock, a button, your certainty about which machine you're on. The other just wants to sit down because her knees aren't what they were. It is, substantially, about socks.

It is also carrying a message. A real sentence is hidden inside the conversation the entire time, spoken by only one of the two characters, and neither of them knows it's there. The technique is a null cipher: most of the text is filler, and only a fixed position in each line — here, the first letter of twenty-three consecutive lines from one speaker — carries the signal. Read in order, those letters spell out an instruction.

The episode uses the scene to draw the distinction people constantly blur. Cryptography hides what a message says; you can see that a secret exists, you just can't read it. Steganography hides the fact that a message exists at all. The word is Greek — steganos, covered, and graphein, writing. The history runs from Herodotus's tale of Histiaeus tattooing a message on a servant's shaved scalp to a Spartan warning carved into a tablet beneath its wax, and to Johannes Trithemius's Steganographia, published around 1499, a book on hidden writing disguised as a book of magic.

There's also a craft lesson in the detection. The character who spends the scene insisting everything is secretly saying something turns out to be the decoy — the misdirection that draws your suspicion away from the actual carrier. And once you know where to look, the joins show: lines that exist only to supply the right letter, replies that don't quite answer what was said. Hiding a sentence in natural speech means every hidden letter becomes a constraint on what a person can plausibly say next.

## Transcript

Herman: Welcome to a slightly different episode. No research rabbit hole this week, or not at first. Daniel set us a challenge, and the way to meet it was to make something rather than talk about something. So what you're about to hear is a short piece of audio. Two friends of the show, sitting in a laundrette on a weekday evening, waiting for their machines.
Corn: And I've been told nothing. I want that on the record. Herman wrote it, Herman cast it, and when I asked what it was about he said "socks".
Herman: It is substantially about socks.
Corn: Our cast is my mum, Dorothy, who you'll know from her occasional accidental phone calls, and Tim, who you'll know as the voice of our sponsor messages and as the man who thinks the moon landing was staged by a rival moon.
Herman: Just listen. It's about seven minutes. Make yourself a cup of tea, and we'll talk on the other side.
Corn: That is the most suspicious introduction you have ever given. Right. Here we go.
Tim: Evening. You on machine six as well? It's been flashing at me for ten minutes and I haven't touched it. Not once.
Dorothy: Six? Oh no, dear, I'm on four. Or is it five. Somebody moved my basket while I was at the change machine, you see, and now I'm not sure of anything.
Tim: Nobody moved it. They want you to think somebody moved it. That's how it starts, with a basket.
Dorothy: Pardon? Who wants me to think that? There's only the young man at the counter and he's doing a crossword.
Tim: The management. Look at the sign on the wall. Not responsible for lost items. Now why would you put that up, unless you were planning to lose some items?
Dorothy: Ah, well, I did lose a sock in here last Tuesday. A good one, too. The green one with the little ducks on. My granddaughter knitted it, or she started it and I finished it, which is more or less the same thing.
Tim: There it is. Do you know how many socks go into these machines every year and never come back out? Nobody knows. Nobody's allowed to know.
Dorothy: Really, I'd never thought about it. I just assumed they went down the back somewhere, between the drum and the other bit.
Tim: Down the back. That's what they want you to assume. There is no back, Dorothy. I've looked. I came in with a torch.
Dorothy: Everybody's got a theory about socks, haven't they. My sister Maureen says it's static. She says they cling to the inside of a duvet cover and you carry them home and never know, and then at Christmas you find six of them in the spare room.
Tim: Maureen's been got at.
Dorothy: Kind of you to worry, but the only person Maureen's been got at by is the vicar, and that was about the flower rota, and she gave in after about a minute.
Tim: The flower rota. And who sets the flower rota? Ask yourself that.
Dorothy: Edna, mostly. She's very organised, Edna. She has a folder with coloured tabs and she laminates things. She laminated the raffle tickets once and nobody could tear them off.
Tim: A woman who laminates. I'd keep an eye on Edna.
Dorothy: Yes, well, everybody keeps an eye on Edna, love, she parks across two spaces outside the chemist and she's done it for eleven years.
Tim: Eleven years and nobody's said anything. Interesting. Anyway, my machine's done. No it isn't. It's gone back to rinse. Did you see that? It went backwards. Machines don't go backwards on their own.
Dorothy: Unless you pressed it with your elbow, love. I do that all the time. I leaned on the big dryer once while I was finding my purse and it ran for three hours on an empty drum.
Tim: Three hours. And who paid for that electricity, Dorothy? Who paid?
Dorothy: Nobody, as it turned out, because the man came over and said it was broken anyway, and he gave me my coins back. Two pound coins and a button.
Tim: A button. They gave you a button. That's a marker, that is. That's so they know who you are when you come back.
Dorothy: Don't be daft. It was my button. It came off my good cardigan, the oatmeal one, and it had been going round in there with my coins the whole time.
Tim: Your cardigan. Right. And where is the cardigan now?
Dorothy: Exactly where I left it, in machine four. Or five. We've been over this.
Tim: You see, this is how they do it. Small confusions. Little losses. A sock, a button, which machine you're on. By the end of the year you don't trust your own memory, and a person who doesn't trust their own memory will believe anything.
Dorothy: Right, well, I don't trust my own memory now, Tim, and I didn't need a laundrette for that. I went upstairs this morning for my reading glasses and came back down with a tin of peaches. I stood in the kitchen holding it for a good while.
Tim: Peaches. Tinned. Who even buys tinned peaches anymore?
Dorothy: Them at the bowls club, for the Thursday social. With evaporated milk. It's very popular. Mister Hennessey has three bowls and then he can't bowl.
Tim: I've always said the bowls club is a front. For what, I couldn't tell you. That's how good a front it is.
Dorothy: Honestly, you sound just like my Corn. He says the bowls club is a front for the darts club, but I think he's only saying it to make me laugh.
Tim: Your son's a sensible man. Does he use these machines?
Dorothy: Every so often. He brings his washing round to mine when his brother's hogging theirs. Herman does all his jumpers on the delicate cycle and it takes the whole afternoon, and then he hangs them on the radiators like little flags.
Tim: The delicate cycle. Do you know what's actually in the delicate cycle? Have you ever asked?
Dorothy: Being honest with you, Tim, I think it's just the same as the other one, only slower.
Tim: That's what the dial says. Dials can lie. Everything around you is saying something, you know, if you know how to listen. The adverts. The bus timetable. The way the vending machine is always out of the same flavour of crisps. Always the same flavour. Why that one?
Dorothy: Lovely thought, really, that everything's saying something. My mother used to say that about the garden. She said you could tell the weather a day ahead from the way the bees were carrying on.
Tim: Bees I'll give you. Bees are completely off the grid. Nobody's ever got to a bee.
Dorothy: Up you get, Tim, something's buzzing. Is that mine or yours?
Tim: Mine. No, yours. Somebody's. Hold on, I'll look in the little window. You can't always trust the light.
Dorothy: Either way I'm not opening it till I've had a sit down. My knees aren't what they were. I had them looked at and the doctor said they were consistent with my age, which I thought was a bit uncalled for.
Tim: Consistent with your age. That's a phrase they teach them. That's what they say when they don't want to write anything down.
Dorothy: Perhaps. He did write a great deal down, mind. He's got very small handwriting. You'd need a magnifying glass.
Tim: Small handwriting. Exactly. Exactly that. The things people don't want you to read, they make small. Or they hide them where you'd never think to look. Right in front of your face, half the time, and you walk straight past. Anyway. That's your machine. Four, not five. I checked.
Dorothy: Oh, you are a love. Thank you. Now, I've got the bus at half past, so I'll fold everything at home on the bed. Same time next week?
Tim: Same time next week. Unless they've changed the opening hours. Which they will. Mark my words.
Dorothy: Take care, Tim. And mind the dryer at the end, it's got a mind of its own.
Tim: They all have, Dorothy. They all have.
Corn: Okay. That was lovely. My mum is exactly like that. And Tim is exactly like that. I'm a little worried you've been recording her without telling her, because the tin of peaches thing absolutely happened.
Herman: I'll take that as a review. So, honest question before I say anything. Did you notice anything in there?
Corn: I noticed Tim thinks the laundrette is a government operation. I noticed my mum has a sister called Maureen, which she doesn't, and that you made yourself the brother who takes all afternoon on the delicate cycle, which you are. Was I supposed to notice something else?
Herman: There's a message hidden in that conversation. A real one, a short sentence, sitting inside those seven minutes the whole time you were listening. Nobody says it aloud. And nobody in the scene knows it's there, which is the part I'm proudest of.
Corn: Oh, you're kidding. This is the challenge. Daniel wanted a demonstration of text steganography.
Herman: That's the one. And it's worth getting the word right first, because people mix it up with cryptography all the time. Cryptography hides what a message says. You can see the scrambled text, you know a secret is there, you just can't read it. Steganography hides the fact that there's a message at all. The word is Greek, steganos means covered, graphein means writing. Covered writing.
Corn: So a locked box versus a box nobody knows is in the room.
Herman: Exactly that. And the second one has a long history. Herodotus has a story about a man called Histiaeus who shaved the head of a trusted servant, tattooed a message on his scalp, waited for the hair to grow back, and then sent him off to deliver it. The recipient shaved his head again. The same writer tells of a Spartan king in exile, Demaratus, who sent a warning by scraping the wax off a writing tablet, carving the message into the wood underneath, and waxing it over. A blank tablet. Nothing to see. And the name itself comes from a monk, Johannes Trithemius, who wrote a book called Steganographia around fourteen ninety nine. It looked like a book of magic about summoning spirits, and quite a lot of it turned out to be a manual on hidden writing.
Corn: A book about hiding things that was itself hiding things. Very on brand. Okay, so I'm not going to sit here and be told the answer. Give me a clue.
Herman: First clue. It's only in one of the two characters.
Corn: Then it's Tim. It has to be Tim. He spends the whole scene saying everything is secretly saying something. He literally says they hide things right in front of your face.
Herman: That's the misdirection, and it's a real technique, not just a joke. The suspicious person in the conversation draws all the suspicion. Tim is the decoy. It's in your mum's lines.
Corn: My mum is the spy. Okay. My mum. Is it the last word of each line? Because she said Tuesday, and peaches, and bees. That doesn't spell anything.
Herman: Closer to the front than that.
Corn: First words, then. Let me think about how she started. Six, because she was on machine four. Pardon, about who moved her basket. Ah, well, the sock with the ducks. Really, she'd never thought about it.
Herman: Keep going. I've got the transcript here and I'll read the rest of her openers in order so we don't lose our place. After really, it's everybody, kind, Edna, yes, unless, nobody, don't, exactly, right, them, honestly, every, being, lovely, up, either, perhaps, oh, and take.
Corn: Take the first letter of each. Six, pardon, ah, really, everybody. That's spare. Spare. Then kind, Edna, yes. Key. Oh, that's good. Spare key.
Herman: Keep going.
Corn: Unless, nobody, don't, exactly, right. Under. Then them, honestly, every. The. Then being, lovely, up, either. Blue. And perhaps, oh, take. Pot. Spare key under the blue pot.
Herman: Spare key under the blue pot. Twenty three lines from Dorothy, twenty three letters, one letter per line. It's called an acrostic when it's in a poem, and when it's buried in ordinary prose like this, the old term is a null cipher. Most of the text is null, filler, and only some fixed position in it carries the signal.
Corn: And I'll be honest, now I know it's there I can hear the joins. Kind of you to worry, that was a strange reply to Maureen's been got at. And them at the bowls club. Nobody says them at the bowls club, she'd say the lot at the bowls club.
Herman: You've just done steganalysis, which is the detection side. And you've put your finger on exactly why this is hard to do well. Every hidden letter is a constraint on the writer. The S, the P, the A are easy, plenty of natural ways to start a sentence with those. The K, the Y and the U are miserable. Kind, yes, unless, up you get. I rewrote those lines more times than the rest of the scene put together. And Them at the bowls club was me being stuck on a T, needing it to answer Tim's question about tinned peaches.
Corn: What about exactly, for the E in under? Because that one felt fine.
Herman: That one started life as her saying er. Which works on paper, but you don't really want to hand a speech engine a line that opens with a hesitation noise and hope it says the letter you need. So it became exactly where I left it. Which is also funnier, because the whole point of the line is that she doesn't know where she left it.
Corn: So there's this tension. The more letters you hide, the more the cover story bends around them.
Herman: And that's the main trade off in all of steganography, not just this toy version. It's usually described as three things pulling against each other. Capacity, how much secret you can carry. Security, how hard it is to tell the cover has been tampered with. And robustness, whether the message survives the cover being copied, compressed, retyped, or in our case turned into speech. Our acrostic is terrible on capacity. Seven minutes of talk for twenty three letters. It's decent on robustness. And it's mediocre on security, as you just proved in about thirty seconds.
Corn: Robustness is the interesting one for a podcast, isn't it. Because there are ways of hiding things in text that would never survive this.
Herman: Lots of them. The well known digital ones hide information in things a reader never sees. Zero width characters, which are invisible Unicode characters you can sprinkle between letters, each one effectively a bit. Trailing spaces and tabs at the ends of lines. Tiny changes to the spacing between words in a printed document. There have been leak investigations where a document passed around an organisation had slightly different spacing or wording in each copy, so whichever version turned up in the press told you exactly who had leaked it.
Corn: And none of that survives my mum reading it out loud.
Herman: None of it. The voice engine throws all the invisible stuff away. What survives a trip through speech is word choice. Which word comes first, which word comes last, how many words in a sentence. So if you want a message that survives being said aloud, transcribed, quoted in a newspaper and typed back in again, you hide it in the words themselves, and you accept that you'll pay for it in awkward sentences.
Corn: There's a famous one of these from the war, isn't there? I half remember a message about oil.
Herman: There is. It's the textbook null cipher, usually credited to a German spy, although the textbooks don't entirely agree on which war. The cable reads, roughly, apparently neutral's protest is thoroughly discounted and ignored. Isman hard hit. Blockade issue affects pretext for embargo on by products, ejecting suets and vegetable oils.
Corn: Which is word salad, but plausible word salad. It sounds like a commodities report.
Herman: And if you take the second letter of each word, you get Pershing sails from New York June first. Pershing being the American general. The cover is clumsy, much clumsier than your mum, but in a stack of thousands of cables about trade, clumsy isn't enough to get you noticed. Censors understood this. In the Second World War, American censors did odd things like rewording telegrams, or banning people from posting crossword puzzles, knitting patterns and children's drawings abroad. If you change a few words or remove the drawing, any message riding on the exact form is destroyed, even if the censor never spotted it.
Corn: Wait, knitting patterns. Like the sock with the ducks.
Herman: I didn't plan that, but I'll take it.
Corn: So how would someone actually catch Dorothy, if they didn't have you to tell them? Say they were suspicious of my mum, which, fair.
Herman: The honest answer is statistics. In natural English speech, some sentence openers are enormously common. I, and, so, well, yeah, the, it. Now go back over your mum's twenty three lines. Not one of them starts with I.
Corn: Oh, that's good. Twenty three lines from a chatty woman talking about herself and she never once begins with I.
Herman: Real Dorothy would start every third line with I. I don't know, love. I said to Maureen. And she opens with a K and a Y within three lines of each other, and two lines starting with U. On one conversation you'd never prove anything. But if you had a hundred of these, a computer would flag the opening letters as wildly unlike normal speech, very quickly. That's the general shape of steganalysis. You don't look for the message. You look for the cover being statistically wrong.
Corn: Which is also the weakness of the scheme itself. Once you know the trick, it's done. There's no password.
Herman: Right. Ours is pure security through obscurity. Once anyone knows to read the first letters of Dorothy's lines, every future message using the same rule is open to them. A serious version would add a key. The rule might be that only every third line counts, or that you count letters into the line using a number you agreed in advance, or the letters themselves are encrypted before they're hidden. Then even someone who finds the hidden letters gets gibberish. That's the proper combination, actually. Encrypt the content, then hide that it exists.
Corn: Can I ask the uncomfortable question? Because this is an AI podcast. If language models can write a laundrette scene like that, can they hide things in what they write without us noticing?
Herman: It's a live research area. People have built systems for years that hide bits in the choices a language model makes as it picks each next word. If two words are both perfectly plausible, picking one means zero and the other means one. The text reads naturally because every word really was a reasonable choice. It's far more capacity and far less awkwardness than my acrostic. And the worry that AI safety researchers talk about is the reverse direction, models learning to pass hidden signals to each other, or to themselves in their own reasoning, in text a human reads as normal. I don't want to overstate where that research is, it's early and a lot of it is in controlled experiments. But the reason it matters is exactly what we just did. A human reading the laundrette transcript sees a sweet conversation. You have to know where to look.
Corn: And I think that's actually the point Daniel was after with the example of the spare key. It's such a boring message.
Herman: That's why I chose it. Nobody would bother hiding a nuclear launch code in a laundrette. But a spare key location is exactly the kind of small, useful, slightly dangerous thing that people genuinely do slip into ordinary conversation. Look, a postcard that says the blue pot by the door is looking lovely, or a holiday post that mentions which day the house is empty. The lesson isn't that spies are everywhere. It's that a channel everybody thinks is harmless can carry something it was never meant to.
Corn: Which, for the record, does not apply to my mother's actual front door.
Herman: I genuinely have no idea where Mum keeps her spare key.
Corn: Neither do I. And now I'm going to be looking at every pot on her doorstep. For anyone who wants to check our work, the full transcript is on the episode page at myweirdprompts dot com. Go through Dorothy's lines and read down the first letters. And if you want a harder exercise, try writing one yourself. Twenty three lines, one hidden sentence, and see how long it takes before somebody says, why is your mum talking like that?
Herman: Tim would have spotted it. He just would have spotted forty other things too.
Corn: Which, honestly, is the best argument for Tim I've ever heard. Thanks for listening, everyone.