The mother reveals how she met Ted and what she has been doing over the past eight years.

Ted and Barney discusses their viewpoints on knowing things about women. Barney thinks that the more you know the more likely you are to find a deal breaker. Ted wants to know the deal breakers right away, as Robin refuses to go to the mall to cover her secret.

Christmas approaches and Ted wrestles with whether to tell Robin about Barney's intentions involving Patrice, while Marshall and Lily get an early Yule gift, a night away from Marvin, but a case of separation anxiety strikes and threatens to ruin the evening.

The gang learns a new way to get their dates to sleep with them after Ted walks in on Robin's date sitting naked on the couch.

Marshall awaits his bar exam results; Ted introduces his latest girlfriend to the gang, who all see the flaw that Ted has missed

When Ted leaves the bar early to prepare a Thanksgiving feast for his friends, the gang winds up partying all night with The Blitz, an old friend from college who has bad luck. As a result Ted is forced to spend Thanksgiving with Zoey.

Marshall goes on his first real date post-breakup with Lily. Not only do Ted and Barney try to warn him that this girl has got the crazy eyes, but Lily decides to do everything she can to find out about this her and break them up. Also, Barney gets a new name.

Amid sharing stories with her about how members of the gang met each other, Ted's hot new girlfriend has a reaction to the meeting that gets her a high ranking on Barney's crazy scale.

Lily and Marshall have their first Thanksgiving as a married couple; Barney is tortured by the slap bet countdown clock, worrying about when the slap will be dished out.

Afraid they will never get pregnant, Lily and Marshall decide to see a specialist. Robin begins her new job.

Thinking that Bob Barker may be his father, Barney is overjoyed to be a contestant on The Price is Right. Marshall and Lily try sleeping apart prior to the wedding.

With only a half an hour left before the wedding, Robin and Barney panic; Lily and Marshall rewrite their wedding vows.

After Ted and Robin's first big fight, Barney tries to convince Ted that being an architect is an easy in to picking up chicks. Lily and Robin start following his trail after discovering that Ted hit it off with a girl named Anna shortly afterward.

Marshall tries to get used to being single in a world that is very coupled-oriented. Barney intended one-night-stand won't go away. Barney uses Lily to get out of his "horrifying" situation. Lily finds a place to stay.

With everything going wrong on Lily and Marshall's wedding day, to everyone's surprise it's confirmed bachelor Barney who tries to fix it all.

It's still Marshall and Lily's big wedding day but now we're at the reception. Robin tries to tell a story but keeps getting interrupted. Barney tries his hardest to figure out Ted and Robin's secret.

Ted pursues a woman named Stella, but only gets attention from her receptionist Abby.

When Ted is packing his stuff for his move to New Jersey, he discovers that the gang was going to hold an intervention for his engagement to Stella and demands they hold it anyway.

Barney gets emotional when he opens up to Honey about his life. Ted admits to having feelings for Zoey to the group.

The gang works together to plan a legendary bachelor party for Barney.

As the gang prepares to go to Robin and Barney’s wedding, Ted invites Lily to see the house he's finally finished fixing up. Meanwhile, Robin and Barney’s night of relaxation is ruined by an obnoxious couple, and Marshall takes the baby on a last-minute trip to Minnesota to see his family.

Barney's efforts to hook up with women are being thwarted by a mysterious woman from his past. Barney and the gang must sift though his many past flings in an attempt to find out who she is.

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 is 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.

While on a trip to Minnesota, Ted and Barney try anything to make Marshall laugh. Marshall runs into an old nemesis from high school.