We have a slang section that contains a glossary of slang and a separate one of Cockney Rhyming Slang. However, care should be taken when using slang. Firstly, it has a short lifespan and words come and go- what's fashionable one week may sound ridiculous a week later. Also, slang is often used by groups as a means of identification, so its use by an outsider might sound strange- the use of the slang of young people by an older person is almost inevitably scorned and laughed at. Slang can also be used within a very small area- a word used in one district or by one group may make no sense elsewhere.
Slang is, however, a fascinating and very creative area of language, and one that is growing in importance as its use becomes more widespread. Slang terms are now used on television and is not uncommon to hear them use in area like politics, where they would once never have been heard.
We add slang to the section as we come across it, and it is more intended as a reference source to help with meaning than as a source of words to be used. If you want to use slang, be careful about where you say it, unless it is standard slang, and try to use it the way you hear others use it. Also, try to monitor carefully how people respond to it.