Definitions by Jack of Facts

beastfuck 

When you're fucking someone with such tenacity that they (and most likely you) lose the ability to formulate words or thoughts having to do with anything besides getting fucked harder, thus at the level of dumb BEASTS.

Oh, I beastfucked her. All she could do was make noises like a paint can being shaken.

beastfuck by Jack of Facts April 9, 2011