Unfortunately, a fairly common argument from opponents of same-sex marriage is that legalizing marriage between a man and a man or a woman and a woman will lead to things like weddings involving, say, a man and a turtle, or a woman and a dolphin.
Well, a couple people are actually embracing that argument instead of rejecting it. Below, a video from the comedy singing duo of Garfunkel and Oates in which the two rejoice in the prospect that, finally, they'll legally be able to have sex with ducks when and if same-sex marriage is legalized. (Hat-tip to Andrew Sullivan.)
By the way, and I don't want to ruin the joke or anything, the video is based on the premise that Pat Robertson said same-sex marriage would lead to duck marriage. But from what I can tell, what Robertson said was that new hate crimes legislation would protect people who like having sex with ducks. It was Bill O'Reilly who suggested that man-duck weddings could be down the road.