I remember once I was sleeping over with a friend. We were sharing a bed.
I remember being in that weird half awake-half asleep state, and I was petting her elbow (her arm was bent). I remember thinking it was a water bottle and I decided I should bite it. My teeth were just a few centimeters from her elbow before I realized what I was doing and stopped.
I can imagine what would have happened if my poor friend woke up to me biting her elbow.
Also, I have no idea why I thought a water bottle would be something to pet and then bite.