I had a girlfriend once who particularly enjoyed biting my penis. She once confided that she wanted to bite it off. I was so horny that I said O.K. From then on the game was afoot. She tried her hardest to behead me so to speak. As hard as she tried, though, she was unsuccessful. She continued to try on a regular basis, but to no avail. I would end up with uncountable bite marks and copious bruising, but intact. Unfortunately for her, she had the dullest teeth on the planet. They were like corn seeds or pine nuts, without any sort of edges. I have to say, it was still quite a bit of fun, and I learned that I could climax by pain alone.