When Ted pulls an all-nighter working on a pitch in an attempt to bring business to his fledgling architecture firm, Marshall tries to lure him to the roof for a surprise 31st birthday party. Barney professes his love for Robin and the story of the Goat is continued.

Stella’s boyfriend Tony breaks up with her after having a conversation with Ted, prompting Stella to come back to Ted with a surprising request.

Barney plans to celebrate his 200th female conquest in style, but ends up with a less than desirable partner. Marshall is obsessed with charts and graphs. A string of seemingly meaningless events causes Ted to run into a former girlfriend–Stella…

When Ted breaks Barney and Marshall’s “three days rule” by having a “text” relationship with a girl he just met, they play a cruel joke on him by pretending to be her. Although credited, Lily does not appear in this episode.

Ted’s plans to make his own design firm in his apartment hit a snag when his personal assistant begins sleeping with Robin, and Marshall tries to find a way to make himself indispensable at his workplace.

When Barney hears that Ted has made a list of things he feels the gang is too old to do, he attempts to complete every task on the list within 24 hours to prove Ted wrong.

In a counter bet, Ted attempts to do things only old people would do. Marshall and Lily’s coaching styles clash when Marshall takes over Lily’s kindergarten basketball team.

When Goliath National Bank cancels plans to build their new headquarters that Ted was hired to design, Barney and Marshall concoct an elaborate lie to keep Ted from knowing he is out of a job. Meanwhile, Robin has a juicy story about a Canadian celebrity.

Ted becomes angry with Lily when he finds out that she has been sabotaging all his relationships that she did not approve of, including his relationship with Robin.

When Lily and Marshall hear that Ted’s college girlfriend, Karen , has moved to New York City, they explain to Barney and Robin how much they dislike her.

The episode name was previously known as “Marshall Forgets his Pants” as to Marshall forgetting his pants when going to his work’s gym before work.

When Barney mysteriously leaves MacLaren’s, the gang follow him to a house in Brooklyn, finding that Barney has a wife and child they never knew about.

Barney explains that it is all a ruse to please his mother, whom they also meet, and that “Betty” and “Tyler” are actors. Betty and Ted are caught in a kiss, which finally forces Barney to confess to his mother. Marshall is upset when Lily admits she hates his mother.