Ted meets Marshall at a college bar. Marshall goes there monthly to make sure his skee ball record stays undefeated. Marshall informs Ted that his co-worker Jenkins will be joining them. Jenkins is a hilarious new lawyer at Marshall’s law firm. Ted thinks Jenkins is a man, but he ends up being a very pretty woman.
The next day, Marshall is in an office meeting with Jenkins when he gets a call from Lily that her class was cancelled and is on her way up for a surprise lunch. When she gets there, a nervous Marshall introduces Lily to Jenkins. Lily doesn’t even flinch at Jenkins being a girl. This makes Marshall suspicious.
Later he talks to Robin and Ted and they tell Marshall that the reason why Lily didn’t flinch is because Lily believes she settled with Marshall and has nothing to worry about. This infuriates Marshall. After multiple hypothetical questions, she confirms his suspicions. She tells him she does think that she is the settler and he is the reacher.
Marshall devises a plan to get Lily and Jenkins together to watch him play skee ball so that Lily will get jealous. When he goes to invite Jenkins she attacks him with kisses. Marshall freaks out and runs home.
He tells Lily and she does not believe him.
Meanwhile, Robin finds popularity from all of Ted’s students. He doesn’t understand why they are watching it; until they inform him it is because that turned it into a drinking game. Every time Robin says, “but -um” you have to take a shot.
That night, Ted and Barney play the drinking game and get totally wasted. The next day at the bar, Ted couldn’t help but inform Robin of the game. She uses this information to get revenge on Ted and his students by saying “but um” a million times getting everyone completely hammered.
The next day, Marshall goes to confront Jenkins and finds out that Jenkins got wasted playing the “but-um” game. She then went to work, made out with Marshall, and had sex with a random stranger.
Marshall tells Jenkins that he told Lily. Jenkins feels totally bad and asks Marshall if she can personally apologize to Lily. Knowing that Lily didn’t believe him, Marshall decides it is a great way for Lily to believe him and make her jealous. Once Jenkins apologizes to Lily, Marshall learned to never let Lily get jealous because she beat the crap out of anyone who tries something with her man.