Episode:

Season 7: Episode 12

Symphony of Illumination: ­Robin tells Barney that she might be pregnant: she hasn’t had sex with Kevin, so it’s Barney’s. Robin has never wanted children and her stance is confirmed when she sees a formerly elegant couple exhausted and disheveled from parenthood. At the doctor, Robin is told that she’s not pregnant, but she’s infertile. This devastates Robin and she covers to the gang by she is ineligible to compete in the Olympics as a pole vaulter as a metaphor to explain why she’s upset. Eventually, Robin comes to terms with her infertility because she knows that she’ll never be alone, thanks to her friends.  Meanwhile, Marshall is determined to decorate his house in the suburbs with the most spectacular Christmas lights display and enlists the help of a neighborhood teenager named Scott, who looks up to Marshall as a father figure. However, Scott was only using Marshall, and throws a party in the house while Marshall is trapped on the roof. ...