"Which brings us to April 25, 2008, my 30th birthday," SagetTed says. He says it would later be referred to as "The Day of the Goat." We cut to Lily on the rooftop, wearing a party hat. She's among partygoers. She tells someone on the phone, "Hey, where are you?" Barney is in his limo, outside Ted's office. Lily tells him that Stella is already there and there's something so awesome, she won't even tell him what it is. "Goat in a party hat?" Barney asks. "Dammit!" Lily says. The goat has a party hat. It's funny. Lily says that he still has to come see it. The camera zooms in on the goat as SagetTed says, "In a few short hours, Lily would come to regret those words." Cut to the goat in the bathroom, bleating. "But... we'll get there," SagetTed says. Argh! Not cool! Barney hangs up the phone. Ted gets into the limo with Barney. Lily, back at the party, asks the goat if she's excited. Quick close-up of the goat as horror music plays.
The limo. They're leaving the city. Ted asks where they're going. "Vegas," Barney answers. Ted asks about the roof party. Barney says that a roof party is happening, but they're not going. Barney says that Ted's other friends want him to drink flat beer 10 feet above his apartment. "But not me, brah," Barney says. He's arranged for a private jet, the Valderrama suite at the Bellagio, steaks at Boa, Scotch at Ghostbar and then ringside seats to watch Floyd Mayweather go 10 rounds with... "Wait for it"... a grizzly bear! Holy shit! I want to be 30 again! Ted, annoyed, tells Barney to take him home. Barney says there's something he wants to tell Ted, but wanted him to be in the best frame of mind before he heard it. "You slept with Robin," Ted says flatly. The limo comes to a stop. Hey, Ranjit is the driver! Ranjit can't believe Barney slept with Ted's ex-girlfriend. He starts cursing Barney out in another language. Barney closes the window to shut out his own guilt. "When'd you find out?" Barney asks. Side-whoosh to the apartment. Right at the moment Marshall was about to open his soda can, Ted called for Robin. Ted is showing Robin an old photo of the two of them from a trip they took as Marshall opens the can and spills it all over himself. The photo Ted has is of a vacation they took to Vermont. Ted offers to let her kept he picture. "I slept with Barney!" she says suddenly. She says it was just one time, right after she got dumped by Simon. She says she was vulnerable and that she wanted to pretend it didn't happen, but she can't. That sounds a lot like she's blaming Barney for taking advantage, when that's really not what happened. Ted looks stunned. She asks if they're still friends. Let a brother think about it! Ted instantly says they're still friends. She asks if he's mad. Ted says he feels weird, but he's not mad. We side-whoosh back to the limo. "Wow," Barney says. "So you're not mad?" Barney asks. "No! I'm not mad!" Ted lies, in a high voice. Ted says that they broke up a year ago, he's with Stella now and he's fine with this. Barney says he's so relieved. Ted says offhandedly that his mom is coming into town next month. "MAYBE YOU'D LIKE TO NAIL HER, TOO!" he screams. Er, I guess he's a little mad.