Cockney rhyming slang is a form of English slang which originated in the East End of London. Many of its expressions have passed into common language, and the creation of new ones is no longer restricted to Cockneys. Up until the late 20th Century, rhyming slang was also common in Australian slang, probably due to the formative influence of cockney on Australian English.

It developed as a way of obscuring the meaning of sentences to those who did not understand the slang, though it remains a matter of speculation whether this was a linguistic accident, or whether it was developed intentionally to assist criminals or to maintain a particular community.

Rhyming slang works by replacing the word to be obscured with the first word of a phrase that rhymes with that word. For instance, "face" would be replaced by "boat", because face rhymes with "boat race". Similarly "feet" becomes "plates" ("plates of meat"), and "money" is "bread" (a very common usage, from "bread and honey"). Sometimes the full phrase is used, for example "Currant Bun" to mean "The Sun" (often referring to the British Tabloid Newspaper of that name). There is no hard and fast rule for this, and you just have to know whether a particular expression is always shortened, never shortened, or can be used either way.

Some substitutions have become relatively widespread in England, for example to "have a butcher's" means to have a look, from the rhyming slang "butcher's hook".

This style of rhyming has also spread through many English-speaking countries, where the original phrases are supplemented by rhymes created to fit local needs. Creation of rhyming slang has become a word game for people of many classes and regions. The term Cockney rhyming slang is generally applied to these expansions to indicate the rhyming style, though arguably the term only applies to phrases used in the East End of London.

It is often used in films (such as Lock, Stock and Two Smoking Barrels (1998), which contains a glossary of Cockney Rhyming Slang on the DVD version to assist the viewer) and on television (e.g. Minder, EastEnders) to lend authenticity to an East End setting.

Some rhyming slang is rooted in the era it's used and is destined to be lost. For example the 1980s, "Kerry Packered" meant "knackered" and currently the term "Britneys" to mean beers, via "Britney Spears", may not outlast Britney's own career.

Other examples of Cockney Rhyming Slang, or phrases inspired by it, are:

Adam and Eve = believe = as in "would you Adam and Eve it?"
Almond Rocks = socks
Apples and pears = stairs
Aris = Aristotle = bottle & glass = arse (a two-stage rhyme) [see Plaster below]
Artful Dodger = lodger
Ascot Races = braces
Aunt Joanna = piano
Bag of fruit = suit
Baked Bean = queen
Baker's Dozen = cousin
Ball and Chalk = walk
Barnaby Rudge = judge
Barnet = Barnet Fair = hair
Berk or Burk = Berkeley Hunt = cunt (used as an insult, never as an anatomical reference)
Boat = boat race = face
Bob Hope = soap
Boracic (freq. contracted to brassic) = boracic lint = skint (i.e. penniless)
Bottle = bottle and glass = arse (i. e. courage; Courage also happens to be the name of a brewery)
Brahms = Brahms and Liszt (classical composers) = pissed (i.e. drunk)
Brass Tacks = facts
Bread and Honey = money
Bricks and Mortar = daughter
Bristol = Bristol City = titty (i.e. breast)
Brown bread = dead
Bubble = Bubble & Squeak = Greek
Butcher's = butcher's hook = look
Chalfonts = Chalfont St Giles = piles (i.e. haemorrhoids)
Chalk Farm = arm
China = china plate = mate
Cobblers = cobblers' awls = balls or 'bollocks' (i.e. testicles, but usually meant in the sense of 'rubbish' as in "You're talking a load of cobblers")
Cock and Hen = ten
Creamed = cream crackered = knackered (i.e. exhausted or beaten)
Currant bun = sun or The Sun newspaper
Daisies = daisy roots = boots
Darby and Joan = moan
Dicky = dicky dirt = shirt
Dicky or Dickie = dickie bird = word = as in "not a dickie", or even "not a dickie bird"
Dog = dog and bone = phone
Duck and Dive = skive
Ducks and Geese = F--k-in' Police
Duke of Kent = rent
Dukes = Duke[s] of York = fork, i.e. hand, now chiefly when balled into a fist
Dustbin Lid = kid
Emmas = Emma Freud (English author and columnist) = haemorrhoids
Farmers = Farmer Giles = piles (slang for haemorrhoids)
Flowery Dell = (prison) cell
Frog = frog & toad = road
George Raft = draught
German bands = hands
Ginger = ginger beer = queer
Gregory = Gregory Peck = neck, or cheque
Gypsy's = Gypsy's kiss = piss
Hampsteads = Hampstead Heath = teeth
Hampton Wick = prick (i.e. penis)
Half-inch = pinch (i.e. steal)
I suppose = nose
Jack = Jack Jones = alone ("On my Jack" = "On my own")
Jam jar = car
Jam tart = heart
J. Arthur = J. Arthur Rank (1930s UK flour magnate and film producer) = wank (i.e. masturbate)
Jimmy = Jimmy Riddle (unknown person, not the character killed during the Waco siege)= piddle or widdle (urinate)
Jugs = jugs of beer = ears
Khyber = Khyber Pass = arse
Kick and Prance = dance
Lady Godiva = fiver (i.e. five-pound note)
Lionels = Lionel Blairs (English variety performer) = flares (as in flared trousers)
Loaf = loaf of bread = head ("use your loaf")
Lucy Lockett = pocket
Mickey Bliss = piss (as in "take the Mickey" = "take the piss" = satirise)
Minces (or mincers) = mince pies = eyes
Mutton = Mutt and Jeff = deaf = named after Mutt and Jeff, two early 20th century comic strip characters
Nobbies = Nobby Stiles (English footballer) = piles (haemorrhoids)
North and South = mouth
Oily rag = fag (i.e. cigarette)
Ones and twos = shoes
Orchestras = orchestra stalls = balls (Orchestra stalls = part of a concert or other hall. Example = "A kick in the orchestras.") [Coincidentally, "orchi-" is also the Greek root meaning "testicle."]
Peckham Rye = tie (i.e. necktie)
Pen and Ink = stink
Pigs ears = big beers (large glasses of Ale)
Plaster = Plaster of Paris = Aris = Aristotle = bottle = bottle and glass = arse (a three-stage rhyme)
Plates = plates of meat = feet
Porky = pork pie = lie, e.g. "He's telling porkies!"
Pony = pony and trap = crap (note: Cockneys also use "pony" to mean £25 - hopefully the meaning is clear from the context)
Rabbit = rabbit and pork = talk
Raspberry = raspberry tart = fart (as in "blowing raspberry/ies" = making rasping noises with your mouth)
Richard = Richard the Third = turd (lump of faeces)
Richard = Dicky Bird = bird (slang for girl) but also Dicky Bird = word
Rosie = Rosie Lee = tea e.g. "Have a cup of Rosie"
Round the houses = trousers
Rub-a-dub-dub = pub = public house
Ruby = Ruby Murray (popular singer in the 1950s born in Belfast) = curry
Salmon and Trout = snout
Scarper = Scapa Flow = go (as in "run for it!")
Septic = septic tank = Yank (slang for an American)
Sexton Blake = cake
Sherbet Dab = (taxi) cab
Skin = skin and blister = sister
Sky = sky rocket = pocket
sweaty = sweaty sock = jock = Scottish person
Syrup / sirrup = syrup of figs = wig(s)
Tea leaf = thief
The Sweeney = Sweeney Todd = Flying Squad, a special division of the Metropolitan Police; used as the title of TV series The Sweeney
Taters = Potatoes in the mould = cold
Titfer = tit for tat = hat
Tod = Tod Sloane = own (as in "on your tod", meaning "alone")
Tom and Dick = sick
Tomfoolery = jewellery
Treacle = treacle tart = sweetheart
Trouble = trouble and strife = wife
Vera = Vera Lynn (famous British wartime singer)= 'skin' or cigarette paper, eg, "got any Veras?", or chin, or gin
Whistle = whistle and flute = suit = as in "a nice whistle"

See also: Polari, Language game