i enjoy having my penis bitten, but not to the point that it breaks the skin. The best place, for me, to have someone bite is around the head of the penis where the base of the head where it meets the shaft. i read one story once where a woman bit through the head of a man's penis, but this would be going way too far for me. Depending on how sever the wound is and if it's gone untreated, a man can actually die from this as the penis is pretty much full of blood during an erection and completely free flowing. Don't know any karate moves, but in a situation like this if the man is fighting back and trying to seriously resist, propping his back up against the wall and pushing the person's face back with his knee would probably be his best choice. He could do the same with his foot too, maybe even digging his toes into the other person's eyes or pushing against the nose. There's a pressure point on the lower part of the nose, the little cartilage between the nostrils that if pushed up against from below will cause a person intense pain. If you want to feel it, you can take your pointer finger and place it above your lip and push it up against this point, never seen anyone do this fully to themselves because of the severe pain it causes. This is a tactic you can use to break up a fight when you pull a person off the other from behind (believe me, that person won't resist if you've got him held this way). All you need to pull them off is your finger under the nose pressing up against this pressure point and your other hand on their chest to guide them back, they'll be totally docile because of the pain it's that intense. But anyway, the person in your story wouldn't want to do the knee to the jaw as his manhood would be inside the mouth and doing so would probably cost him his member.