Yeah, I had no idea what Polari was either. To Wikipedia!:
Polari (or alternatively Parlare, Parlary, Palare, Palarie, Palari, Parlyaree, from Italian parlare, “to talk”) was a form of cant slang used in the gay subculture in Britain. It was revived in the 1950s and 1960s by its use by camp characters Julian and Sandy in the popular BBC radio show Round the Horne, but its origins can be traced back to at least the 19th century. There is some debate about how it originated.
The Polari bible is difficult to read and makes no sense whatsoever. So it’s an improvement.