It happened to me before in a nightclub. I was with my girlfriend at the time and a girl grabbed my crotch right in front of the bouncer. I asked the bouncer what is he going to do about that and his response was, "what's wrong with you, are you bent or something." To be honest I wouldn't be the type to make a big deal out of it, I just wanted to verify the response I was expecting.
It's just a fact of life, there are things only men can get away with and there are things only women can get away with. We just have to accept that and get on with it.