A mysterious tape arrives for Barney from one of his numerous ex-girlfriends, and the entire gang watches it. But, in order for them all to find out how she broke Barney's heart and made him into a suit-wearing bachelor, everyone must share their most embarrassing moment.

When Barney loses his way with women, he hopes a trip to the Victoria's Secret Fall Fashion Show will help him regain his form.

In an attempt to deliver a devastating final slap to Barney, Marshall explains how he mastered the Slap of A Million Exploding Suns.