After knocking him unconscious, [Charlotte] Gainsbourg bores a hole in Dafoe's leg with a hand drill and bolts him to a grindstone to keep him from escaping. Then, she smashes his scrotum with some sort of blunt object. We don't actually see his testicles become disengaged from this body, though it's apparently implied. Next, she brings him to a climax with her hands and he ejaculates blood (yes, it's shown).
Later, in an extreme closeup, Gainsbourg cuts off her own clitoris with a pair of scissors.