Fantabulosa: A Dictionary of Polari and Gay Slang – “Polari has been the secret language of British gay men and women throughout the twentieth century. Like all slang, Polari is an ever-changing vocabulary. Derived from words used by criminals, circus artists, beggars and prostitutes, it also employs elements of Italian, Yiddish, French, rhyming slang, and backslang.”
Also: “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. 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. Polari featured heavily in the “Julian and Sandy” sketches on the BBC radio program “Round the Horne” in the late 60s, and this is how a lot of people first heard of Polari.”
Scrolling through the list on the second link surprised me… a lot of those words are a common part of the gay community today.