4. Last House on the Left (1972) Biting Off More Than You Can Chew
In Last House on the Left two parents discover that the group they are sheltering for the night are the murderers and rapists of their young daughter. Hatching a plan to get revenge, the girls mother takes on of the fiends outside, with promise of some oral pleasure. She bites off his penis. Totally fair, ideal resolution in my opinion, however as a man with certain appendages, I certainly crossed my legs during this scene. http://youtu.be/h48GdjoSsY0