Some years ago I was at a party at which someone was holding forth on the same theme... all men are monosexual, those who claim otherwise are being influenced by society rather than by genuine attraction, yadda yadda.

I replied "That makes sense! Take my case, for example: I've been in a monogamous same-sex relationship for fifteen years, and everybody knows it, but I claim to be bisexual so my boyfriend and I can maintain homosexual privilege... no, I mean heterosexual privilege... no, wait, I'm sorry, how does that work again?"

That was fun.