I had that happen when I was 17. Jack fell over and pinned my pants to the ground with the rear drum. Luckily it missed my thigh. Scared me enough to never do it again. I washed my underwear when I got loose and "walked" home. I should have known better after watching the "Faces of Death" videos in the 80s.I won't let anyone around me do it that way. I do not want anyone under the rig or have lots of soft squishy bits under it or in a position to be unable to jump quickly out of the way if something stupid happens.
p.s. Google it. It's disgusting and real.