XD EDWARD EDWARD EDWARD EDDIE!!XD I wanted to post him on too...he was the first answer that came into my mind XD!!!EDWARD EDWARD EDDDDDIIIIIIIIEEEEEEEE!!!!!!
As Much As I 愛 Ed (from FMA),he does have a quite a temper when it comes to being called Short (well I can't blame him for that) as well as when the word "Milk" is mentioned,but part of this is what makes Ed so awesome!X3
Deidara has a bad temper (especially if あなた ignore him when he's talking about art...and あなた don't even want to see him when someone insults his art O_o )
Sumika from Sasameki Koto. She threatens a lot but never has actually hurt anyone...and with that black ベルト in Karate I don't think I'd want to make her mad lol. Before she met Kazama she used to think everyone was just immature and not worth being around o.o