Ted breaks up with Stella but immediately wants to take it back after a life-changing experience. However, Stella doesn’t realize that he broke up with her. Meanwhile, Barney has a serious accident on his way to see Ted in the hospital.

Barney helps Abby get back at Ted by staging a fake proposal, but Abby doesn’t realize that it’s fake. Lily decides to sell some of her paintings so that she and Marshall can pay for floor repairs at their new place.

When Ted breaks Stella’s trust by telling the gang that she hasn’t been intimate in five years, he must face the consequences of derailing the relationship. Meanwhile, since his split with Ted, Barney searches for a replacement Bro, finally settling reluctantly on his hapless co-worker.

Barney is upset because he violated his own “bro code” by sleeping with Robin. How will Ted react when he learns that Barney slept with his ex-girlfriend?

Robin’s old boyfriend, Simon, from another of her teenage pop videos comes to town , leading to a rekindling of their former romance, and Barney being thrown into a frenzy to find the second video in question, which also features Alan Thicke and Tiffany.

Ted, Lily, and Marshall ponder their former personalities being brought back in the presence of old friends. When Robin is dumped by Simon again, Robin feels vulnerable leading her and Barney to sleep together.

Marshall cries in front of his boss after he chews him out, and everybody gives Marshall their own unique advice on how to confront his boss about the situation.

One of Barney’s exes is sabotaging his love life, but he doesn’t know who. So he makes a NCAA Basketball Tournament-style bracket to figure out which women he wronged the worst.

When Ted goes to see a dermatologist named Stella to have his tattoo removed and instantly falls for her. She’s not interested, however, and so Ted sets out to change her mind before the ten sessions are up. Abby , Stella’s secretary, has a crush on Ted.

Ted and Barney go out in the town to celebrate St. Patrick’s Day as if there is no tomorrow, where Ted is seemingly rewarded for every bad behavior. Meanwhile, Lily and Marshall discover a major flaw with their new apartment, the floor is slanted. Robin helps them invent “roller luge”. Ted finds a yellow umbrella that may be “Mother’s”.

Ted asks the dermatologist removing his tattoo to go on a date and his friends try to discourage him from going out with someone he sees regularly–the “Platinum Rule”–recalling their own horror stories of bad experiences.

(Robin dated a coworker, Barney dated Wendy the waitress, and Marshall and Lily double-dated with their neighbors). Ted’s date is a bust anyway as the doctor says it’s illegal to date patients.