At MacLaren's, in April 2013, Ted passes up Barney's invitation to watch Robots Versus Wrestlers: Legends because he has to prepare for class.
Meanwhile, Marshall brags about a fancy cocktail drink he had invented called the Minnesota Tidal Wave, and attempts to order one at the bar.
He is shocked when Carl the Bartender calls it The Robin Scherbatsky; it is named in her honor because she had ordered it several times.
Future Ted states if he could relive the events of that night, he would have instead visited his apartment, his friends, and most importantly, the mother (who was living several blocks away at the time).
Ted introduces himself, telling her how much he loves her, that they will meet in 45 days, and he would give anything to spend that extra time with her before getting punched in the face by her boyfriend.
[1] TV.com's Bill Kuchman praised Bob Saget's narration and added that the episode's climax stands up there with some of the show's finest moments.