They get laughed out of the room. That'll never happen. The ole "I laugh, so it is defacto untrue" argument.
Update: (and bump)
You know, I've been thinking more about this. My wife was just asking why "Sister Wives" is on TV? It's illegal. Why are they not being prosecuted?
Answer? Nobody's going to press charges. Because it's going to go down to religious prefrence, probably. And if you can say polygamy is wrong, then you can say gay marriage is wrong. Which goes against the progressive activist narrative (judicial and otherwise). There is no right or wrong. Just personal preferences. Right?
So... again, what's next?
Why can't I marry my sister? We love each other, and man, she's hot! Inbreeding? Don't worry. Ok, we won't have kids. Any time she gets pregnant, we'll just have an abortion. Or maybe we will. We'll adopt kids. And so what if we do have kids? Birth defect? Who are you to judge? They wouldn't be handicapped... they'd be handicapable.[/waynesworddreamsequence]
Crazy, right? Really? Is it?