I fidget a lot of my hands and fingers. Sometimes, I open and close things repeatedly (such as the cases for my glasses). Or, I will snap and unsnap something. Or, I will tear of paper into little balls. Or, I will trace my fingers around an object repetitively. Or, I will twist my pen in my hands. Anything.
If my wife is with me, she always seems to notice. And, always asks me to stop. Which is really annoying.