That is called "Daggering" and has been going on for years, here are some reports on the injuries caused by it :P
http://www.google.com.jm/search?q=br...ient=firefox-a
You would think that would be enough to stop the guys from doing it but no...LOL
Here is a video that shows it is best to watch and not participate:
http://www.youtube.com/watch?v=zvzRdQBIC6s
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Tracy