I don't do it, I could never do it (bleh!) but my dad does.
Anyway, he always just sits on the sofa, sucks his thumb, and he cuts off any silk clothes tags he finds, and he rubs it together between his fingers while sucking his thumb. He's done this for all the years I've been in the world, and more. I don't think he ever grew out of it, or found to like it later on in his life.
Another thing he does is stand and rock his knees back and forth, one at a time. Imagine the "dad dance" or being on a cross trainer, one leg in front of the other, but his feet stay in place. He just rocks one leg forward, one leg back, and keeps switching over.
I wonder if any of you do either, or both?