S06E24 Challenge Accepted

Marshall is feeling down, so Lily decides to get them both some of their favorite soup. But shortly after eating it, Lily gets sick and begins throwing up. Desperate to stop Marshall from eating any, after an attempt to call him, she runs from the school to meet him at the house. She stops him just before he takes a bite - of his third bowl.

Marshall has an important business meeting with a prospective employer and has a countdown set to when he'll begin vomiting as well. While at the meeting, he resists vomiting, despite a plethora of disgusting images and stories that the employer tells. Eventually, he gives in and tells the employer he is set to vomit soon and runs out of the room.

Discouraged that he probably blew his chance at his dream job, he comes home and just wants to get some rest before his "countdown" finishes. He awakes in the morning to find out that he hadn't gotten sick at all; it is revealed that Lily was throwing up because she is pregnant.

Meanwhile, Barney and Ted are arguing about who is going to press the button to blow up The Arcadian. After much deliberation, Barney decides to give the privilege to Ted. Before this, though, Ted is distraught with what to do about the lighting for the new building, and, as he has done before, decides that this warrants getting back together with a recent ex-girlfriend - in this case, Zoey. He decides to meet her and buy her an orchid like he first did for her, but Barney and Robin stop him before he can. While on their way to stop Ted, they have a tender moment, but ultimately decide that they both need to move on. Soon after, Barney meets Nora again, and asks her to coffee - and Nora accepts. Robin is visibly upset as she sees that Barney wants to get back together with Nora, hinting that her feelings for him may be resurfacing.

The episode then flashes-forward to the wedding first seen in "Big Days", where Ted and Marshall are sitting outside the church, and Ted is then called in by Lily. Ted goes inside to check on the groom, who is revealed to be Barney.