There’s no bone in the penis, but it sure can break. It’s called a penile fracture and it’s painful! Very vigorous sex or an abrupt change in position can cause the corpus cavernosa -- the cylinders that become engorged with blood during an erection -- to rupture and the crack heard around the world will be his penis. His bruised and bent penis will require surgery, says Roshini Raj, M.D., author of What the Yuck?! The Freaky and Fabulous Truth About Your Body. To lower the chance of this actually happening to your beau, Ian Kerner, Ph.D, author of Passionista: The Empowered Woman’s Guide to Pleasuring a Man, suggests starting in the missionary position and then gently rolling over if you want to be on top. We’re not saying tone it down in the bedroom. Just be careful!