Season 4: Episode 16 - Sorry, Bro

Sorry, Bro: When Lily and Marshall hear that Ted’s college girlfriend, Karen, has moved to New York City, it immediately becomes clear that they can’t stand her. They tell the gang about how pompous Karen was and how she cheated on Ted. They insist that Ted stay away from her, but soon find out that Ted has not only already called her, but that they have gotten back together. Meanwhile, Marshall tells a story about forgetting to bring dress pants to work which Barney finds hilarious.