Oh man, I've got a great one I heard from my friend:
Her friend Claire was making love with her boyfriend, him on top. Suddenly he collapsed onto her, saying something like "Oh my f—ing gawd!" She asked what was wrong.
It turns out, her kitty had been near the foot of the bed watching. And apparently, it became fascinated by one aspect of the view: the balls swinging back and forth. And as a fascinated cat will do, it batted them.
(No claws were involved, thank goodness.)