I once bit my sister on the forehead when I was half-asleep. But I was like... 12 at that point. We had to share a bed on vacation, and I thought her forehead was my pillow (what that has to do with anything, I'll never know), apparently? After I bit her and she yelled at me, I said "Oops. Wrong object" and then rolled over and went back to sleep.
It left a mark on her forehead for a few days. *witch cackle*
And yeah, ~9 years later, she and I still share a bed when we're traveling. She was a bit apprehensive about it for a little while there, though... Can't imagine why.