As Stella finally gives Ted an answer on his proposal, Barney realizes that he may be in love with Robin.

Barney, Lily, Regis Philbin, Robin, Marshall and Ted set out on a mission to find the restaurant in which Marshall ate his first New York burger.

Ted tries convincing his friends that city living is much better than living in the suburbs by inviting them to Stella’s apartment in New Jersey. Stella shocks him by announcing that she wants to live there permanently once they marry.

Ted insists that his friends attend an intervention after learning that they had previously ditched it for his engagement to Stella.

Ted and Stella makes the decision to get married in three days. But then when the day comes it’s not all what they had imagined because of the presence of their exes.

When Ted unexpectedly runs into someone from his past, that he would rather have stayed forgotten, the gang starts wondering how they would handle it, if it happened to them.

Lily and Marshall receive different views on whether they should have a baby when Lily asks Ted and Marshall turns to Robin for advice.

Robin meets back up with a group of over-indulging single party girls known as the Woo Girls. Meanwhile, Barney receives a submission for design of the new company headquarters from Ted.

Robin meets a group of single girls who like to go out. Meanwhile, Barney and Ted discuss a new company headquarter design.

Ted tries to prove to the gang that he’s not a loser after being left at the alter. Meanwhile, Barney and Ted decide to pick a fight with the guys sitting in their favorite booth to impress Robin.

Ted’s younger sister comes for a visit; meanwhile, Marshall introduces Robin to her first theme bar.

When Ted and Robin decide to be friends with benefits to end conflicts around the apartment, Barney tries to fix their problems so they will stop sleeping with each other.

Lily comes back from a trip to Seattle only to run into a blizzard, which may threaten an airport ritual of meeting Marshall. Meanwhile, Ted & Barney offer to keep watch over the bar at MacLaren’s while awaiting their dates, since Carl wants to close up early.

Robin discovers she must find employment within four days or be deported back to Canada, and agrees to create a video resume with Barney’s help.

Suspecting he has a secret girlfriend, the gang follows Barney when he leaves MacLaren’s....

When Lily and Marshall get wind of the fact that Ted’s college girlfriend has moved to New York, they decide to reveal to him how much they hated her.

When Karen comes across another woman’s earring in Ted’s bed, he learns that Lily put it there on purpose leading Ted to discover this isn’t the first time she’s covertly meddled in his relationships.

As a means of protecting Ted from discovering he has lost an important job, Marshall and Barney dream up an intricate lie.

When Barney learns Ted has a list of things he thinks the gang is too old to do, he sets out to do every task within 24 hours in order to prove Ted wrong.

Ted decides to use his apartment as his new architecture firm and hires an intern, but she becomes a bit too friendly with Ted's buddies.

Ted breaks one of Barney and Marshall's relationship rules, texting a woman he recently met, so the pair play a joke on Ted by pretending to be the woman.

Ted explains to his future children how important it is to be in the right place at the right time. Meanwhile, Barney celebrates his 200th conquest.

Tony, Stella’s fiancA©, makes an attempt to ease the burden he feels for ruining Ted’s life, by helping him find a job, but instead proves that no good deed goes unpunished. Meanwhile, Barney wants to prove that he can get out of a speeding ticket.

Trying to keep his architecture firm afloat by doing an all-nighter, but Marshall tries to lure him to the roof for a surprise 31st birthday party, on the fourth season finale.