[Citation needed]
Well, here: http://phenomena.nationalgeographic.com/2009/12/22/ballistic-penises-and-corkscrew-vaginas-the-sexual-battles-of-ducks/
[Citation needed]
Well, here: http://phenomena.nationalgeographic.com/2009/12/22/ballistic-penises-and-corkscrew-vaginas-the-sexual-battles-of-ducks/