The episode begins and Robin and Barney are engaged, but Ted was "definitely not happy," Old Ted says. But perhaps it's Marvin, who won't stop crying. Lily and Marshall can't figure out the problem. Marvin is constipated and Lily tells Ted that she misses Marvin's diapers full of confetti. That's what she says to save Ted from the truth while he tries to eat his chili. Robin shows up at the bar and Lily immediately pushes her way into the wedding planning. Lily wants to set a date and Ted chimes in, "May 25, 2013". Ted has already offered to help with the planning and pulls out a massive binder.
Ted starts going into some of the details, including the location and colors, and Lily is enraged. "I'm gonna cut you, bitch" Lily screams as she leaps across the table to choke Ted. Marshall asks Robin how Barney is doing and she reports that his panic attacks are getting further apart, so that's progress. In Barney's apartment Robin asks him if he's asked for her father's permission. Barney laughs this off and goes on about how crazily old-fashioned this sounds. Back at the bar, Robin reminds the gang how her dad "is a little scary". She recounts taking Barney to lunch to meet her dad, who shows up and scares the crap out of Barney with one look.
But her dad takes off his jacket and reveals a Hawaiian shirt and says that he and "Carol" go there all the time. He's been living in New York for eight months. He's also on Facebook and wants Robin to respond to his friend request. He says Carol has helped him appreciate things and made him "fun". Still, he's not impressed with Barney's hair, saying grown men are not blond. Robin gets up to go to the restroom, leaving Barney alone with her dad. Before Barney can even say anything, Robin's dad leans forward and says, "Permission denied". The next day, Barney meets Robin Sr. at the same restaurant and reveals a new dark hair color.
Robin Sr. leans forward and tells Barney, "When I wanted to marry Robin's mother, I slaughtered a whole family of bears with my bare hands. I gave the pelts and the bear meat to her father as tribute. You know what they call that in Canada? Manners". Back at the apartment, Marvin is still crying and not pooping. Robin gets another friend request from her dad on Facebook and says she's just going to accept, but Marshall and Ted jump forward and tell her not to do it, with Marshall adding, "You don't want to see what's behind that door". Robin asks what Marshall is talking about and Ted interjects, saying, "he's talking about my mom's 2,000-word review of '50 Shades of Grey 14 of those words were vulva".
Robin Sr. in the meantime is at Barney's apartment urging Barney to pull the trigger of the gun he's pointing, but Barney can't do it. Turns out, there's a live bunny sitting on Barney's coffee table. Robin walks in and sees the situation and Barney tells her that her father is crazy. Robin, however, wants to ask her dad about the fact that his Facebook page says he's married. He explains that he and Carol were at Key Largo for a concert and "one thing led to another" and they got married. Robin says that if he doesn't want to involve her in his life, she won't involve him in hers and proceeds to tell her dad that she and Barney are already engaged.
She tells Robin Sr. he can't come to the wedding. Marvin is still crying, but Lily comes in and says she booked the wedding band's manager to see who booked the band and they gave her Ted's phone number. Ted goes into a little speech about how he didn't want Robin to have an unreliable band, and it soon becomes clear that he doesn't want Robin to marry Barney. Lily takes Ted up onto the roof so they can talk it out. In order to get Ted to admit what he's thinking, Lily gives him an out that will make him not the worst person on the roof. She confesses that "sometimes I wish I wasn't a mom; sometimes I want to pack a bag and leave in the middle of the night and not come back".
Ted, then, admits that Robin shouldn't be with Barney she should be with him. Lily goes on to talk about how art used to be her whole life, but she hasn't picked up a brush in months. She ends by saying, "It's just really, really hard". She tells Ted they both have to accept their lots in life, she has to be "a mom to a beautiful, wonderful, if slightly constipated, little boy, and you have to let Robin and Barney get a band". Barney brings Robin Sr. to the restaurant and her dad apologizes for getting married without telling her. Barney thinks that's it, but Robin Sr. goes on to say that in order to fix this he's going to divorce Carol.
Robin tells him she just wants him to be a normal dad, and go to her wedding and smile for the pictures and dance with her. He doesn't quite agree to this, but agrees to one dance to "Cheeseburger in Paradise" with Carol singing. Four months later, Ted is shown explaining to his ex-girlfriend Cindy that the wedding is one week away and the band canceled just like he thought they would. "When will people realize I always know what's what?" Ted asks her. "He says to the lesbian he dated for a month" Cindy replies, with her wife sitting next to her.
Ted asks if they know any good wedding bands available at the last minute, and Cindy's wife asks Ted if he believes in destiny. They just had lunch with her ex-roommate, who is a bass player "in the best wedding band in the tri-state area" Cindy says. They had a wedding scheduled for that date, but it fell through at the last minute. Ted figures it's a lucky thing he ran into them, but Old Ted tells the kids that "lucky doesn't even begin to describe it because if Robin and Barney would've taken my advice and hired a DJ, I never would've met your mother". The episode ends at this point.