Barney: How would you like to extend your stay here? All you'd have to do is pretend to be my wife, and scare off the occasional one-night stand. I know, I know, you've got your ethics, you've got your principles...
Lily: I'll do it.
Barney: Really?
Lily: Barney, you've clearly got some serious mother issues that have left you the emotional equivalent of a scavenging sewer rat. But, in my other apartment, I would be living with an actual scavenging sewer rat, so you win.