I was wondering what everyone else does. At the start of my night I sometimes with friends sing this as loud as possible while walking down the street. Then start improvising more embarrassing lyrics. It's hard but it works.

http://www.ultimatecampresource.com/site/camp-activity/hey-bob-billy-bob.html

Sometimes it helps just to think of just anything (legal) that puts a lot of awkward attention on you. When nothing bad happens you can go from feeling really anxious to totally in state.

Another one I know is to take turns saying something like "penis" and try to say it louder than the person who went before you. I rarely do that one myself.