Image: Francis C. Franklin
Ready for a biological fact that part of which sounds like something Will Ferrell would exclaim in an Anchorman movie? National Geographic explains that sex by force is common among fowl. Yet female ducks have a built-in defense against such forced frolic. Their corkscrew-shaped vagina spirals in the opposite direction of male ducks' genitalia. If the male tries going for any action the female isn't in favor of, she contracts the walls of her genital tract to make entry impossible.
Learn 21 more odd facts concerning animal couplings here. -Via The Week