We see the group at the pub as usual, with Barney struggling to contain his laughter. He thinks that something involving Marshall is overwhelmingly hilarious, and finally persuades Marshall to tell the story, which he does over the course of the episode. To make a long story short, Marshall was playing basketball at the gym like he does many mornings, but this time he forgot his work pants, so he went to the office in gym shorts and called Lily. Lily, upon her arrival at Goliath National Bank, ran into Barney before she made it to Marshall’s office. Barney took the pants and delivered them to Marshall, but not before making some “creative alterations.” Marshall had to give an important presentation to a laughing crowd in pants reduced to tattered short shorts. At the end, we see that he still has them on.
On to the actual content. Ted tells the group that his girlfriend from high school and college, Karen, has moved to town. This announcement is met with groans from Lily and Marshall. Apparently Karen was even more pretentious than college-age Ted, which is quite the tall order. Flashbacks reveal that she wasn’t exactly faithful, either. She would always cheat on Ted by sleeping with a jock in Ted’s own dorm room (the jock would always offer a monotone “Sorry, bro” as an apology), then the two would break up. After a short span of time, though, the two would get back together, mainly because Ted is a pansy.
All this time, Ted has been talking to the group in the context of potentially having dinner with Karen at some point in the future. He reveals that not only did the dinner already happen, but the two have been sleeping together for days (Incidentally, Karen is still as pretentious as before). Again, more groans. Ted accuses Lily of hating Karen because “she lingered” when she walked in on Lily painting Marshall in the nude. The group warns Ted that it’s going to end up like before and that he’s going to walk in on her in flagrante delicto with some meathead.
This time, though, the tables have turned; it turns out that Karen has a boyfriend, and Ted is the one with whom she’s cheating on him. Ted learns this when the boyfriend in question walks in on them, at which point he gets immense satisfaction from dropping a casual “Sorry, bro.” In reality, though, he’s angry. Afterwards, he gives Karen a piece of his mind, vowing to never see her again. Apparently, Karen gave her boyfriend the breakup talk that Ted never got, so she’s grown as a result of all this.
…but how could Ted have known this? Well, he’s still a pansy, and the two are back together and dating. Karen walks into the bar at the end of the episode.
Marshall: “I want to eat your brain but only if it’s organic and grass-fed!”
Barney: “A hug is like a public dry-hump.”
Marshall: “I think you’re hugging wrong.”
Ted: “We’ve all done things we regret. Junior year Marshall grew a soul patch, wore a rasta hat, and asked everyone to call him MC Smooth.”
Marshall: “I don’t regret that for a second, Ted, what are you talking about?”