How I Met Your Mother

Recap

When Robin refuses to go to the mall and the gang is betting on reasons why not, Marshall and Barnery propose a "slap bet."  Marshall believes she was previously married and Barney believes she was a porn star.  We find out that it was because Robin was a pop star and had a hit about going to the mall.  Marshall is awarded five slaps to be given whenever he wants.  He uses one this episode.