I am pretty much that super gentle person that most people can't imagine me getting that angry. But oh, can I get angry. >__>
So when I do, I typically hold it in long enough for me to get out of the situation, so that I can calmly evaluate the situation later. If I react immediately, I am going to be rash and most likely make a decision I will regret later. So if I wait, I can make a more rational decision. Granted, I haven't been in to many situations like that, so I can't say for certain what I would actually do.
The only time I was ever really pushed to that edge was when I was in seventh grade, my younger brother had just started kindergarten, and it was the first day of school. Some other kindergartener had punched my brother in the stomach for no reason, so I ran right over. I WANTED to smack him upside the head, but all I did was grab him by the arm and ask him why he did that. He punched me in the mouth as a result. >__> So yeah. I learned to take a step back from things from that. xD