The (NSFW) money quote:
"We’re talking about taking the penis of a man and putting it in the rectum of another man and wriggling it around in excrement. And you have to think, would I want that to be done to me?"
News flash to Nancy: a lot of married opposite-sex couples, including many of your constituents, practice anal sex. Sorry, honey — like it or not – they just do.
And it takes a particularly filthy and depraved mind to make the issue of same-sex marriage about excrement. But even if that were somehow relevant, sodomy laws were repealed in New Hampshire over a quarter of a century ago.
But the real issue isn't what Nancy would or wouldn't want "done to her". The real issue is whether or not Nancy should be in a position to make that decision for other people.
P.S. And what about lesbianism, Nancy?