Any person, usually male, who is perceived as wimpy or unmanly. Used when referring to toughness, bravery, or simply breaking the rules. Boys who are whipped by their girlfriends fit under this definition as well. Momma's boys are poonfucks. Poonfuck has nothing to do with one's ability to do something; it is objective to whether or not they will try it.
The Poonfuck did not go jet skiing with his best friends because he would rather spend time with his girlfriend.