I was messing around on a rail the other evening and hit my back peg on the way up. Immediately I hit the upright and got the rail between my legs. Not only between my legs but exactly between the butt cheeks. You know the webbing between your fingers if you splay them out? Imagine ripping that tissue. Apparently there is the equivalent above my asshole and having the rails diameter spread my intergluteal cleft tore it.