Ted teases that Marshall must have left the right answer in his pants, because that's exactly what didn't happen. Saget!Ted narrates during the flash back which can be boiled down to this: One afternoon, Karen and Ted were having sex at her place, when some guy walked in, was shocked to find her in bed with someone else, and Ted sniffed out a, "Sorry, bro." Saget!Ted says, "So this time, the meathead Karen was cheating with..." Flash forward to MacLaren's. Current-day Ted says, "...Was me. Ted. Me." He again tries to direct the conversation to Marshall's pants story. Marshall gets all self-righteous about Ted now being complicit in breaking some guy's heart. He pokes Ted with his finger -- his voice but a growl. "And you! You of all people know exactly how that feels." Robin calls Marshall out on really not wanting to tell the pants story. Barney chants like a two-year-old, until Marshall finally gives in. As we already know, he called Lily for pants. Flash back to GNB. Lily brings him a pair, I suppose because she's got this thing about other people lingering on her man's junk, but who knows. She's in a hurry, though, so when she runs into Barney, she tells him she's in a hurry but came by to give something to Marshall. Barney's mind goes to the gutter. Well, strictly speaking that's where it lives, yeah? So after some double entendre about her "giving it" to Barney and Barney then "giving it" to Marshall (Barney says, "I don't know about that. I mean, yours would have to be really good"), Lily explains that Marshall forgot his pants and asks Barney to deliver the new pair from her, so that she can dash off. And this B-plot has only been funny all along, because it's not funny at all -- to anyone but Barney. And here's the funniest part yet... to Barney. He licks his lips. "It's a good thing that you came by, because he has a really important meeting today, and it would be pretty embarrassing, a-a-a-and not at all funny... if he were to show up... not wearing pants. So... I'll make sure he gets these." Lily hands over the pants and takes off.
Flash forward to MacLaren's. Ted accuses Barney of not delivering them. Barney says, "Theodore Evelyn Mosby!" Hee. "Of course I gave him his pants. I gave Lily my word. My word is oak." Oh, dear. I think he just turned into Beau Bridges in Jerry Maguire. Barney considers his drink and smiles. "Although... I did make some alterations." Flash back to GNB. Barney makes like Edward Scissorhands and Renfield's lovechild as he -- shall we say -- tailors Marshall's pants. Cut to Marshall's meeting. He's handing out a contract, but the guys all razz him asking him when he joined AC/DC, and suggesting that the Oliver Twist auditions are down the hall. Everyone laughs and the camera zooms out to give us a full shot of Marshall, and his now knee-length, jagged-edged pants. Barney adopts a British accent that makes him sound more like Ricky Gervais' David Brent, than poor Oliver: "Please sir. May I have some more... pants?"