Cockney rhyming slang is a form of speech originating in the East End of London. It is an amusing and arguably a widely under-estimated part of the English language.
Some slang has become so prevalent in everyday speech that many Londoners wouldn't realise they are using it. Some substitutions have become relatively widespread in Britain, for example to "have a butcher's" means to have a look, from the rhyming slang "butcher's hook". As in this example, the slang uses substitute words, normally two, as a coded alternative for another word. The final word of the substitute phrase rhymes with the word it replaces. Where only the first word of the replacement phrase is used the meaning is hard for the uninitiated to guess. There lies a form of coded speech.
"Use your loaf and think next time" (loaf of bread = head)
"You will have to speak up, he's a bit mutton" (mutt'n'jeff = deaf)
"I'm going on my tod" (tod sloan = alone, or own)
"Are you telling porkies?" (porkies = pork pies = lies)
"Are you going to rabbit all night?" (rabbit and pork = talk)
"Did you half-inch that car?" (half-inch = pinch, meaning steal)
"I haven't heard a dicky bird about it" (dickie bird = word)
As a predominantly spoken tradition the exact origins of Rhyming slang is difficult to trace. The first written references to a Cockney dialect and culture date back to the 17th century when regional folk traditions first started to be recorded by writers and academics. There are, however, few explicit references to Rhyming Slang itself in this time. The first detailed account of the actual phrases came in 1859 when John Camden Hotten published his book: The Slang Dictionary.
Even if we could be certain when it emerged it would still be difficult to explain why. A popular claim is that rhyming slang was a secret way for London street traders, the costermongers, to conceal their often illicit practices from eavesdroppers and the recently established police force.
Rhyming slang certainly developed as a way of obscuring the meaning of sentences to those who did not understand the slang. It remains a matter of some speculation whether this was done simply to have some linguistic fun, or whether it was developed intentionally to assist criminals.
Cockneys are well known for their eloquent wit, gift for phrase making and nicknaming. This has enriched the English tongue with new forms of speech; clichés and catchwords that have not only spread through the housing estates of East London but have travelled many, many miles out of earshot of the sound of Bow Bells around the English speaking world.
Slang has continued to grow, reflecting new trends and wider usage throughout many English-speaking countries. Back in its spiritual home of London, recent research suggests that a new mix of Cockney and Bangladeshi is developing. Nonetheless, the traditional Cockney accent is still alive and kicking. It's most noticable out in Essex, the main reason being that after the Second World War, many East End inhabitants moved to such new towns as Basildon and Harlow. When they resettled, they took their speech with them.
Phraseology that is recognisably "London" in everyday use includes "leave it out", this means something like "don't be silly"; "gercha!" means anything from "you liar" to "go away"; "give us a bell" means "phone me"; "geeing up" is teasing; "old man/woman" is father/mother or husband/wife; "old geezer" is an old man; "straight up" means "honestly"; "hang about" means "hold on"; "give it some stick" is to perform strenuously; "what's the damage?" means "how much?"; "you're not on !" means, "the answer is definitely NO !"
New slang is constantly being manufactured. There are often variants, sometimes funny and apt, occasionally vulgar and of uncertain origin, but still adding to the power or variety of the English language.