I'm not a nail biter but I always nibble on them never really biting anything off. I do it more when I'm nervous.

I have a hard time looking someone in the eye when being spoken to...always look at their mouth.

Back in elementary and middle school I'd draw all over my margins until they were full and then color in closed in letters like "o". I had to drop this one in highschool after having to rewrite a few papers...