Ted and Robin discover that sex with each other solve their fights as roommates, which makes Barney very jealous and angry. Meanwhile, Marshall reveals that he's too embarrassed to use the office bathroom.
Ted meets with his ex-girlfriend from college--a girlfriend who cheated on him constantly and Marshall and Lily can't stand, and Marshall tells the story about how he forgot to bring his pants to work.
Ted's plans to make his own design firm in his apartment hit a snag when his personal assistant begins sleeping with Robin, and Marshall tries to find a way to make himself indispensable at his workplace.
While Ted struggles with an unorthodox architecture project, Robin finds out that Barney is in love with her, and Marshall threatens to take a long-considered leap from the roof to a neighboring building.
When Lily and Marshall realize that Robin and Barney are the perfect double-date friends, they try too hard to impress and come on too strong. Meanwhile, Ted gets a new nickname from Barney after an unsuccessful hook-up.
Although he vowed to Robin and Marshall that he would never tell them, Ted finally tells his kids that at one time both Robin and Marshall used to smoke. In 2009, they both felt like they had good reason to do so. Marshall, only an occasional smoker, always said that each cigarette was his last. But when his old boss, the meanest man nicknamed Artillery Arthur, became his new boss, he thought he was going to be fired - again. So when Marshall found out that Arthur was a smoker, Marshall used it as a bonding mechanism to keep his job. Robin, at the time anchoring the ...