When I was in school, I'd chew pencils. One boy in my class in Year 1 would eat the bits of pencil that he'd bitten off, but I'd just chew. The reason for this isn't that I was absent-minded: it's that the feeling of having my teeth break wood, particularly my canine teeth, is really satisfying. I'd sometimes just sink in one canine tooth at a time into a pencil, until it was full of little holes.
I don't do this anymore to pencils. Now I use apples.