How do you deal with anger with a friend?

Normally i try to stay as calm as possible and try to see their side so i can just end it. But i have one friend that i cant get what he's thinking and once i just got overly pissed and started yelling. Now when ever he thinks im about to start yelling he kinda goes in to a shell. its a bad feeling making your friends scared.

Its actually hard to get a rise out of me, but when someone does, I like to find a solution to the problem. I am not the confrontational type, so I either back away, or just try and find a common ground to squash the issue. However when it comes to violence, thats something i save for fight-for-your-life purposes.

Overall I just keep a cool composure, and if I loose it I straight out tell whoever I am being angered by what my reason for anger is.