Sometimes when I've had a bad day and people are doing things that really make me angry, I find it useful to do the following exercise.
I imagine that I'm sitting in an interview room in a police station and a very angry detective is shouting at me. He asks me why I murdered the person I'm mad at. What possibly could have driven me over the edge?
And I reply,
"He told me my documentation was incomplete and I had to rewrite it."
"He won't use schema names in his database coding."
"She crashed the server."
"She left the butter out, again."
The whole situation seems so ludicrous that I just have to smile. I also find that saying the word "monkey" in place of any swear words that come to mind adds some levity to the situation (and it keeps me from swearing).