[David]

I wrinkle paper & other foldable material in a very weird way--it can't be described. I've been doing this since I was a child. I used to practically destroy school textbooks, wrinkling each page. Doing so seems to calm me or something.

Let me try to describe the movement. I take the edge of the sheet of paper in my right hand, thumb atop it & middle finger below the thumb but on the underside of the sheet, & then I press the two fingers toward each other, carefully guiding the resultant switchback, or sharp bend, from one end of the scarp (or fault) to the other, until I am left with a sheet of paper with what looks like a single long scar running situationally along the center.

I do this compulsively, practically whenever I have any such material in hand.