Threw a Blackberry against my fireplace. Took my sunglasses off and broke them in half and threw them on the ground. really fucking stupid, but in those two instances I lost it.
Also, in college, my roommates were playing each other in Madden and they had money on the game. Well, my buddy who was winning had to go to class, but my other roommate was a sore loser and kept running plays that kept the game going(not running, throwing every down etc.). He told him if he left and went to class before the game was over, he would not pay him the money. So, dude got pissed and smashed his computer. College was awesome.