Check out this video of people doing amazing (often, quite crazy) things. I figure that it must be a combination of brain chemistry and autonomic nervous system soup that drives people to do this stuff.
Special note to my buddy Denny (the other half of the Elderly Brothers): Pay special attention to 3:46 in the video. I think I saw you do something a bit like that in Helen, Georgia a couple years ago. Yo, I figure that, with a little practice, you could pull this one off.
Thanks to da Chef of da Future for the link.