Take ten minutes with a book or some music. If you can't get any privacy, lock yourself in the bathroom or sit in the car (lock the doors).
Put on some music and dance. The louder, faster and sillier; the better.
Have a good cry. Sometimes we all need one.
Do something out of character for you. If you're the type who always has to act like a grown up and follow the rules, don't. Climb up on the wall next to the sidewalk and walk along it; go out the 'In' door; make faces at each other in the window reflection or do whatever makes you laugh.
Hope that helps a little!
