I hair-pull and then when there's no hair left in that spot, I scratch my scalp. It's a (thankfully) very small spot and it's always the same, and I can go years without having the urge flare up. When it does, though, it seems to come out of nowhere and I can't stop no matter how hard I try. There have been times when I had upcoming haircut appointments and was like "the hairdresser will see it and know," and I still can't stop. So I come up with elaborate stories for what happened instead.