In the two part finale, Barney convinces Marshall to give his son the middlename of "Waitforit" whilst Marshall is drunk at a casino as Lily goes into labor. The first half is their Homeric attempts to get the hospital, finally assisted by a bus full of elderly people. Ted finally makes amends with Robin to just remain friends, and Barney takes his stripper girlfriend to Hawaii. Before they can get aboard the plane, Barney's magic mystery box is scrutinized by security and he, Quinn, and the box are detained as terrorists. In a small room, Barney (NPH with the help of a fellow magician) executes the magic trick centered around the box which produces a ring, and he proposes to Quinn (important because Quinn would only stop stripping if she were to get married, something that irks Barney).

The newly engaged couple visit Marshall and Lily's apartment to see Marvin Waitforit Erikson, while Ted decides to call Victoria as she had been the closest match for him. She arrives at the bar in a wedding dress; she's ready to leave her fiancee for Ted. He opts to drive her back to the church because he knows how shitty it is to be left at the altar. As he arrives at the church he doesn't stop, and he and Victoria drive off in the sunset.

Flash forward to Barney's wedding, where Ted is summoned to talk to the bride. Lily ushers him into a room where the bride is revealed to be Robin.