arm wrestling is all ego, which im not saying is all wrong, a bit of male bravado is fun every now and again, but arm wrestling is just a recipe for disaster.
watch this-
http://www.youtube.com/watch?v=7ME0QRHtCTk
these guys dont even look that strong, i guess when you have guys who are benching 300+lbs the chances are a lot more real. think how long that would put you out of training for.