Student or Learner
when is cockney rhyming slang used? are people in england using it when they tal to eachother?
There are various stories about its original use; one was as a private code for discussing criminal activity in public. CRS made equivalent pairs like 'tom foolery'/jewellery; and users could then say 'tom' to mean jewellery. People don't use it like that.
However, bits of CRS have found their way into everyday speech. When someone calls someone a 'berk' they often don't realize they're using the CRS remnant based on the rhyme 'Berkshire Hunt'. A less offensive example is based on the rhyme 'borage and thyme'/time; people in prison ('doing time') are said to be "doing porridge". Or, in the nursery rhyme 'pop goes the weasel' 'weasel' stands for 'coat' ('weasel and stoat'). There are lots of similar words in colloquial speech. Sometimes they turn up in out-dated slang ('me old china' meant 'my old mate'), though that's not much used now). One expression that is current is the slang word 'taters' meaning 'cold' ('Potatoes in the mould').
And CRS hasn't stood still. For example professional wrestlers refer to pretending to have a neck injury as "doin' a Gregory".
Incidentally, I don't recommend the Wikipedia article on CRS. Even the first sentence is misleading and/or wrong: 'Rhyming slang is a form of slang in which a word is replaced by another word or term that rhymes with it. This is not true of much rhyming slang: if you accuse someone of telling 'porkies', you mean they are lying; few people actually spell out the 'pork pies'. If someone is going to the bank to cash a cheque, he might say 'I'm going to the J. Arthur [Rank] to sausage [and mash] a goose's [neck]' but he wouldn't say the rhyming word. People calling a hat a "titfer" often have no idea of the hidden rhyme ['tit for tat'].
Some rhyming slang pairs are spelt out - as in 'Would you Adam and Eve it', but if the speaker went on to say 'I couldn't Adam and Eve my minces' he'd be most unlikely to spell out the rhyme, 'mince pies'. In fact, the plural marker even attaches to the word that doesn't rhyme.
There are even fewer uses of rhyming slang where the rhyming word alone is used: 'tart' is one, used to refer to a woman with loose morals (Jam tart/sweetheart). Here the connection with the rhyming original is so remote that the meaning has changed (there's nothing intrinsically loose about the morals of a woman who might be addressed as 'sweetheart').