Scene is set, two people are having sex.

They're doing their thing, all having a wonderful, happy time.

The guy starts dirty talking to the chick;
"Who's your daddy? You like that, don't you? Oh, god, you're such a bad girl."
Whence the female replies, "You are...! Oh god, Yes! I'm a bad girl!"

And then the guy says: "God, I wish your mom was here to see this."
Girl Goes: "Oh Yeah, My Mo---.... What?"

Courtesy of Yazz. The things he thinks up when we're together. Yeah, that's right.