I do rub my head a lot, especially when driving and stuck in traffic! When i had long hair I used to habitually curl it round my finger, as do my sister and dad (must be a family trait!!) but now I can't do that!! 
I did the same thing when i had long hair (interesting total random side note: in all my dreams i still have long hair
).
For years (before i went sly) i had a very long goatee... i'd always be playing with that.
Now I do the head rub all the time... and like someone else said, i pat my head at times, too. it's kinda funny because when there's music playing i'll sometimes pat my head in time like a drum
