A kid did this to me once. I was playing smash with a few friends at his place after playing d&d. We were 13 or 14 if memory serves. He left the room for something, then a minute later he walks back into the hallway with a rifle, said something to grab our attention, then pointed it at us. Luckily it was a bb gun, but even if I had known that I still would have beaten the shit out of him had my friends not pulled me off him.

Life didn't flash before my eyes or anything, I just froze for half a second then ran at him. He was one of those kids who was as much of an asshole as he could be without being widely considered an asshole, if you know what I mean. Not a complete psycho, just an opportunisticly sadistic motherfucker.