Were you baffled when Don Cheadle's British character in Ocean's Eleven warned that they would be "in barney" if they didn't pull off the job in Reno? Perplexed by all the talk of "custard" and "ping-pong tiddly" in an otherwise-menacing bar scene in the 1998 cult British crime thriller Lock, Stock, and Two Smoking Barrels?

Or have you perhaps found yourself unsure what was being asked of you when a British friend suggested you have "a butcher's" at the restaurant across the street?

Understandable! They were speaking in Cockney rhyming slang, a code-like vernacular invented in 19th-century London. It's almost impossible to interpret until you understand its structure. But once you know its rules, it all makes sense. Sort of.

What is Cockney rhyming slang?

Cockney rhyming slang is a particularly British form of slang with an unusual twist. Whereas most types of slang work by replacing a word with a synonym — like "booze" for "drink" — rhyming slang replaces it with a two-or-more-word phrase that rhymes with the word being replaced, but whose ordinary meaning is totally unrelated to the word it's standing in for. So, for instance, in rhyming slang, "stairs" gets turned into "apples and pears."

That would be tricky enough, but there's a second twist that makes rhyming slang even harder to understand: usually, the word of the rhyming phrase that actually rhymes gets dropped. So even though "stairs" rhymes with "apples and pears," someone using the slang in conversation would just say "apples." To say "go up the stairs" in rhyming slang, you would say "go up the apples."

It can get even more complicated than that. Jonathon Green, a British slang lexicographer who authored The Vulgar Tongue: Green's History of Slang, told me that his favorite rhyming slang word is "arris," which means ass, because it actually goes through more than one round of partially-dropped rhyming. "Arris," he said, is short for "Aristotle," which rhymes with "bottle," which itself is the first half of the phrase "bottles and glass," which rhymes with "ass." So in rhyming slang, "I'll put my foot up your arris" means "I'll put my foot up your ass" — but to understand that, you need to have a working knowledge of both Greek classical philosophers and recyclable containers.

And to top it all off, some of the rhymes are accent-specific. For instance, Green said, "Charing Cross" is rhyming slang for "horse"— but the rhyme only works in the Cockney accent. Likewise, "cold potato" is slang for "waiter," even though in most accents those words don't rhyme.

Where did Cockney rhyming slang come from?

Rhyming slang has been around for a long time. According to Green, its first appearance in a dictionary was in 1857, but it has probably been in use since the 1830s or 1840s. It was most likely invented in East London.

"Cockney," in the most literal definition, refers to a person born in the Cheapside area London, within earshot of the bells of St. Mary-le-Bow.

There is some debate about why Cockney rhyming slang was invented. The most prominent theory, Green said, is that in the 1820s and 1830s, other forms of slang had been worked out by the authorities, so criminals needed a new way to communicate without being understood. Under that theory, rhyming slang was created intentionally, as a sort of secret code.

A second theory is that its purpose was commerce, not crime. Some believe that the market traders of Cheapside made it up so they could communicate with each other without the customers understanding their conversations.

Two less-prominent theories are that rhyming slang originated either among bricklayers or among the Irish "navvies" who were brought in as laborers to build Britain's railroads in the 19th century. However, Green dismissed those theories as less likely, noting that he had never seen an example of bricklayer rhyming slang, and that rhyming slang is almost totally absent from Ireland today.

Can you show me an example of rhyming slang in action?

Sure! Here's a clip from the 1998 movie Lock, Stock, and Two Smoking Barrels:

The bartender is speaking in rhyming slang. Here's the text of the monologue:

Rory? Yeah I know Rory. He's not to be underestimated, you've got to look past the hair and the cute, cuddly thing — it's all a deceptive facade. A few nights ago Rory's Roger iron's rusted, so he's gone down the battle-cruiser to catch the end of his footer. Nobody is watching the custard so he turns the channel over. A fat man's north opens and he wanders over and turns the Liza over. "Now fuck off and watch it somewhere else." Rory knows claret is imminent, but he doesn't want to miss the end of the game; so, calm as a coma, he stands and picks up a fire extinguisher and he walks straight past the jam rolls who are ready for action, then he plonks it outside the entrance. He then orders an Aristotle of the most ping pong tiddly in the nuclear sub and switches back to his footer. "That's fucking it," says the guy. "That's fucking what," says Rory. Rory gobs out a mouthful of booze, covering fatty; he then flicks a flaming match into his bird's nest and the man's lit up like a leaky gas pipe. Rory, unfazed, turned back to his game. His team's won two. Four-nil.

"Roger iron's rusted" means "television is busted." It's a compound phrase of two different rhyming slang terms: "Roger" is short for "Roger Mellie," which is rhyming slang for "telly," itself a non-rhyming British slang word for a TV. "Iron rusted" means "busted." So, he's saying that Rory's television was broken.

"He's gone down the battle cruiser," means "he's gone down to the pub. "Battle cruiser" rhymes with "boozer," another word for a pub or bar.

"No one's watching the custard" means "no one's watching the TV." "Custard and jelly" rhymes with "telly."

"A fat geezer's north opens" means "a fat guy opens his mouth." "North and south" rhymes with "mouth."

"Turns the Liza over" means "change the channel." "Liza Minnelli" rhymes with, you guessed it, "telly."

"Walks straight past the jam rolls" means "walks straight past the assholes."

"He then orders an Aristotle" means "he then orders a bottle" — a little unusual not to have a two-word phrase, but we can let it slide.

"Ping pong tiddly" means "strong drink." "Ping pong" rhymes with "strong," and "tiddly wink" rhymes with "drink."

"Nuclear sub" means "pub."

"He flicks a flaming match into his bird's nest" means "he flicks a flaming match into his chest." Bird's nest = chest.

In other words, this is a charming anecdote about a psychopath who doused another man in hard alcohol and lit him on fire because he had the audacity to interfere with his TV viewing.

Is Cockney rhyming slang still in use?

Yes. People in the UK don't speak in rhyming slang constantly or anything — conversations like the one in the video above are definitely extremely unusual — but there are a number of rhyming slang terms that are in common use. Rhyming slang is pretty kitschy these days, so it can also be a jokey, silly way to speak.

For instance, people often say "I haven't a scooby," which means "I haven't a clue." "Clue" rhymes with "Scooby Doo," so when you drop the second word, a scooby is a clue.

Other common-if-kitschy rhyming slang words include "trouble," which means "wife" (trouble and strife = wife); "butcher's," which means "look" ("butcher's hook" = look); "dog," which means "phone" (dog and bone = phone); and "barnet," which means "hair." (Barnet fair = hair.) And there's "berk," an insult. When I first heard it, I thought it was perhaps a reference to the well-known 19th-Century Edinburgh murderer William Burke. But according to Green, Berk is short for "Berkshire hunt," which rhymes with ... not a very nice thing to call someone.

Celebrity names often get turned into rhyming slang terms. Take, for example, "Posh and Becks," the nickname that British tabloids gave to David Beckham and his wife Victoria, née Posh Spice. Posh and Becks is now rhyming slang for "sex." "Pete Tong," a popular DJ who works for BBC Radio 1, is rhyming slang for "wrong," as in "it's all gone a bit Pete Tong."

"Britney Spears" means "beers." And speaking of beer, "Nelson Mandela" means "Stella," as in Artois.

It could be worse, though. Pity poor Brad Pitt, whose name had the misfortune of rhyming with "shit."