Constantly wanting to get into a fight with someone. NEED HELP!?!

I'm constantly wanting to get into a fight with someone. Today I just want to start a fight with someone. I've never got into a fight with anyone but now I really want to get into a fight and see how much damage I can do to someone. For no apparent reason I'm just really pissed off right now. And I've had a good day so far. But when I got home i just seen this guy that runs his mouth at everyone talk about how he beat up my friend in a fight (which it didn't) And that kid thinks he could beat me up and I just want him to say one wrong word to me and I will fight him. Is it I dont like people talking about my friends or I'm just a really pissed off person? Also lately I've been picturing him talking **** to me on the bus and me just going back there without warning and hitting him, and everytime i picture that I just feel like getting up and hitting him. Is this a anger issue?