AKA the Bird or middle finger. Derived from a feminist request to refrain from clapping and use jazz hands to show appreciation at a conference to as to not 'trigger' attendees by clapping.
SJWs want us to use Jazz hands instead of applause, let me show them my JazzFinger.
Klaxons Slang (Anglo-Klaxon) This is when people are guitar-wanking (showing off a song.) Although it doesn't have to music-related - just something over the top and unnecessary.
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi