Banging your shin. The body is clearly unable to cope with such an unnecessary level of pain. I managed to do it the other day whilst performing a pointlessly-complex move during a play on Skyward Sword. I'm glad I threw the remote at the sofa as opposed to my HDTV.

Also, women who feel it is necessary to use their teeth when performing a popular oral sex act. Obviously, a high level of self-control is needed in this situation. Any violent reaction will definitely spoil the mood and could also lead to a serious hinderance in your future sexual activities...