<P> Barney reveals that he has uncovered a video of Robin and asks her if the name' Robin Sparkles' sounded familiar, which worries Robin . Ted tries to stop Barney from playing the video but Robin lets Barney play it . The beginning of the video shows Robin, dressed as a schoolgirl, seductively pleading with a teacher not to give her detention . Barney, supposedly for the sake of Robin's dignity, pauses the video and slaps Marshall . Robin is surprised to learn that the others think that it is porn, and plays the rest of the video: A 1980s - style bubblegum pop music video where a teenage Robin (referred to as "Robin Sparkles") sings "Let's Go To the Mall". Robin repeatedly sang the Canadian hit on a lengthy tour of malls around the country, causing her to develop a phobia of malls . </P> <P> Lily points out that Barney slapped Marshall without having won the bet and without the permission of the slap bet commissioner . Lily gives Barney a choice: He can be slapped ten times immediately, or five times at any moment Marshall chooses . Barney picks the five slaps . Robin tells Ted that she is glad Ted knows her secret now . They kiss and Marshall suddenly slaps Barney, proclaiming "That's one". </P> <P> The episode was originally titled "Robin Sparkles," but the title was changed to "Slap Bet" in order to avoid giving away the ending . In reruns, CBS used the originally intended "Robin Sparkles" title . In syndication, this episode is titled "Slap Bet ." </P> <P> The menu that Robin makes up when Ted questions her about her wedding was the actual menu at the wedding of writer Kourtney Kang, which took place two weeks prior to the writing of this episode . </P>

What episode of how i met your mother has let's go to the mall