(YouTube link)
Russian tennis player Mikhail Youzhny became angry when he hit into the net during his third round match Monday against Nicolas Almagro at the Sony Ericsson Open in Key Biscayne, Florida. He reacted by hitting himself in the head -and drew blood! He later won the match, and also became a YouTube hit. Link -via Viral Video Chart
I love the random bleachers guy in blue they show after he hits himself. (I guess it may be a coach or something, but the video doesn't really say).
Also, I don't think he was bleeding due to a really hard blunt impact, i think it was probably due to the racket strings actually slicing him a little bit on one of the smacks.
http://en.wikipedia.org/wiki/Boban_Jankovi%C4%87
(could not find the video, but it was, well, striking)