Marshall: Robin is not in porn. I'll bet you anything that she's married.
Barney: $20,000 says it's porn.
Marshall: I don't have $20,000.
Barney: Well then, what do you have?
Marshall: Well...
Lily: No.
Barney: I got it. The ultimate wager. Slap bet.
Marshall: Oh, slap bet. We used to do those when I was a kid.