While atesh's historical survey of it is probably accurate, none of the writeups here convey the contemporary status of rhyming slang. To an outsider -- to an American, say, who's merely aware that such a thing exists, perhaps from hearing snatches in films and TV -- we need to give some better idea of who uses what terms, and when.

Cockney rhyming slang is both a historical curiosity, and a living tradition. Some words have passed into general slang use among the rest of the British people, and indeed in other countries; whereas most of the words in gm_food's long list (above) are incomprehensible even inside Britain. In fact, Australia uses rhyming slang too and has its own, such as billy lid for kid.

There's always been slang, in both upper and lower classes: the romances of Georgette Heyer are full of glorious examples. In previous centuries low-class slang drew quite a bit from Romany and later from Yiddish. I don't know when rhyming slang arose; it doesn't strike me as common in nineteenth-century novels or Punch cartoons, so perhaps it became popular in the early twentieth century, since any cant has to keep up to date and remain obscure to outsiders.

So it's dynamic. A lot of the terms found in lists are dead: invented once, in fashion for a while, and forgotten. No-one actually uses them. Second, it's still alive, mainly for the amusement of Cockneys now rather than secrecy. ("Cockney" isn't derogatory, by the way.) It's common to hear new phrases pop up. The idea is that they should be fairly clever, but easy enough to work out. When you first hear "He gives me the Brads", you quickly think about filling two slots "Brad ----" and "He gives me the ----s", and should get the answer almost immediately. Obviously this isn't a traditional Cockney phrase. The films quoted above are loaded with newly-invented terms. With the recent death of Gregory Peck I saw several letters in newspapers about what he was rhyming slang for: to write someone a Gregory for £10, for example. This use must have arisen when he was young and prominent. But no-one actually says that one these days. This is why I'm going to give a classification of which ones seem to have entered the language on a more permanent basis.

Two final points before I classify them. Usually the rhyming part is dropped off, but not always. It varies phrase by phrase, and sometimes it's optional. So "that's a load of cobblers", never "a load of cobbler's awls"; but to call someone drunk you can say either "elephants" or "elephant's trunk", or indeed "Brahms" or "Brahms and Liszt".

Also, they don't substitute for the word generally, but only in one grammatical form or context: so "pickle and pork" means "walk", the noun, as in "go for a ...", but not as in "... quickly". I've indicated these contexts.

Here's my tentative classification of all the terms mentioned in the above writeups. So if you're an American tourist for god's sake don't tell a stranger you're going up the frog to buy some Uncle Fred.

1. So common in general slang that we might not even remember they're rhyming slang:

Or in other words, if you are a tourist and you say one of these, you won't sound ridiculous.

  • barney = fight, trouble ("a bit of a barney", not "a bit of barney"; ?from Barney Rubble)
  • berk = cunt (only as a mild insult, not usually understood to be "cunt" -- from either Berkshire Hunt or Berkeley Hunt, though in both these the syllable is pronounced "bark")
  • butchers = look (as in "to have a butchers at something"; from butcher's hook)
  • cobblers = balls (usually as "nonsense", rarely literal "testicles" -- from cobbler's awls)
  • loaf = head (usually in "use your loaf"; from loaf of bread)
  • rabbit = talk (usually "rabbit on"; ?from rabbit and pork)
  • scarper = go, flee, escape (from Scapa Flow, the harbour in Orkney)
2. Sometimes used, but we're invariably conscious they're rhyming slang and joking:

Not to be used by foreigners unless you've gone native!

Examples welcomed of terms that are actually in wide use, like the above. The condition is, I have to have heard it already. I'm sure other people will disagree with some of my classifications. Amendments cautiously welcomed.

3. The rest of them.

Forget it. Antique or obscure or spurious. Found only in long lists that are no real help to the contemporary visitor; or facetiously by people who like to be obscure; or coined for some new film that's trying to confuse audiences.

Salon des Réfusés
I've had other people /msg me with these, though I haven't heard them myself:
tWD offers skinner = sister (skin and blister)