1. I make sure there are no people in my vicinity.
2. I conjure up some kind of anger-inducing scenario (anything from wanting to punch a bully, to heroic last stand cliche)
3. Live myself into it.
4. Then I SCREAM MY DAMN LUNGS OUT! AAAAAH!
5. Repeat stage 4 while making sure to not leave stage 3.
6. Once your throat is sore, and/or you've dropped out of stage 3. Calm down, and assess your own stress levels. If you are still stressed, go back to stage 2 (or skip to stage 3 if you still like the current scenario).
Important. Always remember that stage 1 is of the highest priority. This stage overrules all the others. It must not be ignored, lest awkward situations occur.
It works for me. It also helps that I'm good at screaming silently, if that makes sense.
-V