My buddy in college was having sex with a girl. For some reason she locked up on his dick. She had no control over it. He tried to pull out and tore up her whole vaginal area. It had to be reconstructed in surgery.
I guess it is fairly well know that stuff can happen.
I could tell you crazy stories about my ex who was a dominatrix. I have repressed most of them though.
Couple key words... restraints, whips, chains, handcuffs, leather, punches, elbows, slaps, a coffin closing on my head etc.
Huh? I never realized how much I miss that girl!