Not at the moment, but he used to race them - dirt bikes. He's been 'underneath' them a few times, with other riders flying over the top of him! No major injuries though - nothing worse than a few scrapes and bruises. :)
That's cool, I've owned 20+ bikes over the years and about half of them were dirt bikes. I never rode in a sanctioned race, but when we rode on weekends, it usually turned into a no holds bared; "I'm staying in front until I win or crash, blast !!"
Many of those riders were professional racers: Class C flat trackers, Moto-Xer's, Enduro riders, road racers and guys like Dick "Bugsy" Mann who was good at everything.
I stopped riding dirt in '83...I got pissed at the California dirt riding laws...sigh... :o)