I still like my response last time someone stated trying to get in my face about video games.
My response? Explain, in extraordinarily graphic detail, why he was s stupid twit, why he deserved brutal, brutal shotgun murder, and why I wanted to taste human flesh (Which I didn't, but at the time I made everyone think I did by knowing things like the fact that it tastes just like pork when cooked, which you can learn fairly easily be reading the acconts of people forced to canabalism to survive).
Then I stalked him (within the school only to keep it at least somewhat away from the eyes of the law) for about 3 weeks until he had a complete emotional breakdown, and begged me to stop. I didn't for another week. Then I acted as if I had never done anything, which, as you could imagine, creeped people out more.
Yeah, after awhile, no one bothered me, but at the same time, no one spoke to me. Incidentally, this was the other half of my goal in stalking a kid for 4 weeks; creep everyone out to the point that they wouldn't talk to me anymore.