A fanny fart. Often caused by a build up of trapped air during sex, but occasionally by infection. The latter form would also have a very unpleasant odour. Can be used as an expletive.
We were just lying there cuddling when she let out some noisy cunt gas.
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