Polari (also seen as 'Palare') is a gay slang language, which has now almost died out. It was more common in the 1960's when gays had more need of a private slang. In researching Polari, it's difficult to find any written material about it as what little used to exist was out of print. However, in the last few years, more and more people have been finding out about it, and several web sites and magazine articles have been written.
For more info and a word list click here. Thanks to Chris Denning.