Joking or not joking, I don't think this type of ignorant mockery should be taken lightly. If a comedian were to mock someone else's "coming out story" in his/her show, would the same people still laugh - they are trying to get the same effect as this loser is.
Let me tell you people a little story and this is actually a true story I read on one of those online journal things (could be LJ or Xanga, I don't remember right now), but there was this son of an owner of a restaurant and he's known to be a real joker and also clowning around bringing his friends to the restaurant and having a jolly good time. Now one of workers there who have been worker for quite some time is gay and everyone knows so. And one of the night the son of the owner was there with his friends, the gay guy's mother was there as well. And everyone who works there pretty much knows the guy's mother because he frequently visits and what not. So the son of the owner that one night calls the mother over to his table and tells her something along the line of "your son likes it up the ass, right?" and he laughs and his friends laugh and all the mother could do was smile because she was embarrassed by this.
I don't mean to be rude or uptight or whatever else you may want to say but the son of the owner was just trying to be funny, no?