Robin Sparkles

With under an hour until the wedding, Barney and Robin panic while Marshall and Lily work on rewriting the vows from their own wedding.

While trying to find out who Robin's past obsession is, Barney uncovers the lost episode of the "Underneath the Tunes" music documentary series in which Robin Sparkles was featured. Marshall and Lily have some concerns about Ted's latest girlfriend.

The gang learns more of Robin's pop-star days as Robin Sparkles, thanks to a new tape Barney discovers about a Canadian children's show.

A major crisis in Barney and Robin's relationship gives Lily ideas on how to break them up with Alan Thicke's help.

Marshall takes Robin to a bar with a Minnesota theme. Ted attempts to keep his visiting sister away from Barney.

Robin's old boyfriend, Simon, from another of her teenage pop videos comes to town, leading to a rekindling of their former romance, and Barney being thrown into a frenzy to find the second video in question, which also features Alan Thicke and Tiffany. Ted, Lily, and Marshall ponder their former personalities being brought back in the presence of old friends. When Robin is dumped by Simon again, Robin feels vulnerable leading her and Barney to sleep together.

When Robin refuses to go to the mall, Marshall and Barney propose a "slap bet". Marshall believes she was married, and Barney believes she was a porn actress. Robin reveals she was in an embarrassing music video in the mall. Marshall is eventually awarded five slaps to be delivered anytime, and lands his first slap.

P.S. I Love You by Robin Sparkles (aka, Robin Daggers)