Dolphins have weirdly strong penises full of muscles that they can use like hands. In some cases, rape-y groups of “male teenage” dolphins will grab the wrist of a human swimmer—male or female—WITH SAID HAND-PENIS—and pull them under water to a “dolphin rape cave." There they take turns (because they’re polite) raping the human until they’ve had their fun. Obviously, by this point, the person will have drowned. So it appears to be kind of a sucky way to go.

From the very first link from googling. Kinda undid some of the concern for dolphins I had from watching "The Cove"