I know how you feel.
Happens in Raves all the time as well. Haha, I brought my friend to a Rave for his first time, and at one point he was on a platform in one of the dance rooms talking to this guy. I knew this guy was gay so I go up to my friend and say 'Mate, you might not wanna get too comfortable, he's gay'...he goes 'Yeah yeah, don't worry man, we're just talking'...Two minutes later my friend comes running over to me and goes 'Dude, he licked my f**king ear!'. Hahaha, I'll remember that forever.