Polari

Polari was a gay language (or cant) in 1950s and 1960s England. Such languages/cants exist in many other areas (for example both Greek [Kaliarda] and Turkish gays have a distinct language.

This however may be the strangest fact (perhaps the strangest sentence) in Wikipedia

In 2002, Palestinian hip hop act Juha released an album called Polari, with the chorus of the title song written entirely in the slang.

http://en.wikipedia.org/wiki/Polari