Ep 18. Weekend at Barney's

When Robin goes on a business trip to Russia, she leaves Barney in charge of watching her dog, which leads to a wild weekend for the gang.

Barney decides to throw a party at his apartment, but things quickly spiral out of control. Ted, Marshall, and Lily arrive to find that the place is a disaster, with empty bottles and food strewn everywhere. When they ask Barney what happened, he tells them that Robin's dog, which he was supposed to be taking care of, got loose and caused all the chaos.

Despite the mess, Marshall is excited to play a game he's been working on for years called "Marshgammon", a combination of Marshmallow and Backgammon. However, Barney convinces him to play a new game he's come up with called "Barney's New Game". The rules of the game are convoluted and nonsensical, leading to frustration from the rest of the group.

Meanwhile, Robin is having her own troubles in Russia, as she struggles to communicate with her colleagues and acclimate to a new culture. She spends most of her time in her hotel room, feeling lonely and disconnected.

Back in New York, the gang continues their weekend of debauchery, with Barney leading the charge. He convinces Ted to dye his hair blonde, and the group starts a conga line through the apartment. As the night wears on, they become increasingly rowdy, and the party threatens to spill out into the streets.

At one point, Lily accidentally breaks Robin's prized mug, which leads to a heated argument between her and Marshall. They both realize that they've been suppressing their feelings about a recent fight they had, and they finally have a long-overdue conversation.

As the weekend comes to a close, Robin returns home and is shocked at the state of Barney's apartment. She's also disappointed that Barney didn't take better care of her dog. However, she's happy to see her friends and joins in the festivities.

In the end, the gang reflects on their wild weekend and the bonds that they share. They all agree that they have an amazing group of friends and that they wouldn't want to spend their weekends any other way.