After Barney makes an out-of-place declaration that this is going to be a good night, Marshall reaches down and takes a pair of overalls out of his box of mementos, which is conveniently placed on the floor next to his booth at MacLaren's. It's so out of nowhere, I feel like there's a missing scene, but let's just go with it, okay? It's clear Marshall loves his overalls. He calls them "my jam." Robin needles him about being a virgin until he met Lily. Marshall and I find her comment unnecessary, but Lily allows that the overalls just might have been a dealbreaker. Laughing, Barney grabs the overalls from Marshall and says nobody could get laid wearing them. He then stops mid-chuckle and says (to himself, mind you), "Challenge accepted!" He's going to wear the overalls until he has sex with a woman. The gang rolls their eyes as he rushes off to change in the men's room. Robin says, "I actually dated that guy." Everyone makes regretful yeah, you did noises at her (and the writers) until Ted announces his Maggie game-plan. When she arrives, everyone should make nice with her for a moment and then take off. This is Ted's one shot at Maggie and he's determined not to screw it up. So, I guess we know Maggie's not the mother, huh?
Robin asks Ted who's covering his class that evening. Ted yells, "Crap!" and next thing we know, Maggie is there. It's clear she's as fond of Lily and Marshall as they are of her. She and Robin greet one another warmly and then Robin roams away to give the old friends their space. Ted tells Maggie he totally forgot he has to teach that night and asks her if she wants to come with "and check out a real, live architecture class." Maggie says, "Ooh... not even a little bit." [I get that Ted is a colossal bore, but still -- if she was even slightly interested in him, or as good a friend as she seems, wouldn't she be curious to watch him teach a class? ...No, I guess not. - Zach] She'll hang with Lily and Marshall until Ted gets back, so Ted pulls them aside and tells them if they still want him to find the perfect girl so they can all grow old together -- Maggie is that girl. They're not to let any man near her in his absence. No waiters. No busboys. "If she burst into flames, I want a fire woman putting her out." Marshall takes that too literally, and Ted calls him back to the plot. "Damn it, Marshall. Whatever you have to do, keep Maggie Wilkes single until I get back." He starts out of the bar, and then turns back and grabs hold of his friends. "I left my tab open. Don't abuse it." Once his back is again to them, Marshall and Lily high-five, and Marshall rushes to the booth as Lily heads to the bar. Commercial.