The episode begins and Ted shows up at the bar with a story about how he lifted a taxi cab off a trapped woman, but they're all focused on a leather cuff he's wearing on his right wrist. Ted also has a date, which no one believes. He doesn't want to bring her into the bar, but his friends don't want to leave. Then Ted finally reveals that his date can't come into the bar for 6 1/2 months. She's 20 and a half. Ted also reveals that his new girlfriend sells leather cuffs. Robin reveals the engagement ring Barney gave her. Ted realizes he has to end it with this new girl.
Robin comes to the apartment later after Marshall and Lily have started getting it on because Lily is suddenly turned on by the leather cuff Marshall is wearing and is distressed about how her day is going so different than usual. She reminds them that her usual day involves men smiling and giving her bagels, coffee and newspapers for free while singing her songs. But this day, she was charged for her breakfast sandwich. Lily explains to her that "the ring has power". She explains that the ring makes her invisible. Barney sneaks up on Ted while he's sleeping and says Ted has to sleep with the 20-year-old for Barney's sake. Barney explains he loves Robin, but his body is detoxing after years of one-night stands.
After flipping through Ted's phone for pictures of the 20-year-old, which he doesn't find, Barney finds a picture of Ted and winks every time he tells Ted he didn't sleep with his mom. Finally, Ted relents and says he'll "proxy bang" the 20-year-old. Ted tries to claim he won't enjoy, but knows he will. Robin in the meantime is adjusting to her new life because she can't get the bartender's attention. "Normally, New York is the friendliest, most affordable city in the world" Robin says. "Now it's as rude and expensive as San Francisco" she adds. Lily is getting even more into Marshall's whole leather-cuff-wearing persona, and Marshall is now wearing a knit cap and a wallet chain to help her out. He explains to Robin that "picturing me as a loser musician with a Vicodin addiction and a beat-up van I use to steal copper wire really turns Lily's crank".
His wrist is red and inflamed from an allergic reaction, but he won't take it off because it's giving him a chance at sex. Robin is outraged by the idea that the ring is preventing her from getting beer. "I was just getting used to the fact that now I have to pay for bagels and coffee and rent" she tells Marshall, but this beer thing is unacceptable. She moves toward the bar and is blocked by two rows of men who ignore her. She takes the ring off, and they part like the Red Sea to make a clear path. That night, Barney is desperate and having cold sweats. Ted can't get into it because everything they talk about comes back to her fetish about him being old. Ted tells Barney he and Carly don't connect on anything and it's going to be over.
He tells Carly he's not seeing a future between them and she thinks he's dying. Suddenly, her phone rings and it's an R2D2 ring tone. Ted is amazed she likes "Star Wars," and she confirms it. They kiss and Carly says, "I mean I've only seen the new ones". "Close enough," Ted says, and they make out some more. Ted later goes to the bar and gives Barney the good news. Barney says he knew it, he felt some kind of force and it was almost like they were doing it together like it was a "bro-nnection." He asks Ted if he felt that, too, and Ted says he "couldn't have performed" if he had. Barney asks for pictures and Ted, eager to brag, hands over his phone. Barney opens a photo and scrolls up slowly, for effect. Commenting all along the way, he scrolls up to Carly's face and realizes she's his half-sister.
Ted says he couldn't have known. Barney wonders why the universe would have done that to him, and Ted says, "I don't know it’s not like you've ever treated women in such a way that would invite some kind of karmic retribution". Barney now realizes he didn't feel "a bro-nnection, it was a sis-nnection". Back at the apartment, Marshall and Lily are getting into it, but Marshall's hand has now swollen to about three times its normal size. Lily tells him he doesn't need the leather cuff to be into him. She asks him if he can have sex before they go seek emergency medical attention. "There's only one way to find out" he says. They get up to walk to the bedroom and Marshall collapses face-first, on the couch. Barney calls Ted and apologizes for over-reacting. Barney invites Ted to come over and smoke some cigars to reconcile. Ted shows up and Carly soon arrives.
Barney has planned a surprise wedding. At the "wedding" ceremony, Barney reveals that he doesn't agree with one-night stands and Ted has an epiphany Barney’s detox is complete. That means it's a good thing that Ted and Carly hooked up. Barney says its fine, as long as Ted promises he'll no longer sleep with his sister. Ted says fine, and then winks. Barney is upset and asks Carly to promise she won't sleep with Ted again. She does, then winks. Back at the bar, when Barney shows up, Robin realizes the "true power of the ring". She sees Barney more clearly than anything or anyone. Marshall asks Robin if she's figured out how she's going to get drinks at the bar now that she's engaged. "Oh sure," she says. "I know a way that's going to last forever" she adds.
She leans toward Barney and says, "Scotch on the rocks?" "Coming right up" Barney says, heading off toward the bar. Ted walks in wearing a fedora. Before anyone says anything, he stops them and says, "Before you guys ask this new girl's ass is phenomenal" That night at their apartment, Marshall is playing video games when Lily tells him he's going to crack up when he sees the jeans some catalog sent her by accident.
She comes out wearing full-on mom jeans with the elastic waistband and everything. "You look like some suburban mom who drives a minivan filled with stale Cherrios and empty juices" Marshall says, laughing. Turns out, this look is Marshall's fetish. In the end, the two are at it again on the couch. The episode ends at this point.