'The Stinsons' - Season 4, Episode 15
Suspecting Barney's keeping a romance secret from them, the gang follows him and discovers him leading a secret suburban family life.
Air Date: March 2nd 2009.
Barney: Look, mom, there's something I have to tell you, something I should have told you a long time ago. Tyler is dying, and Betty said that when he goes she's gonna off herself. So that's all probably going to go down pretty soon.
Lily: Barney, check it, three blond babies drinking bad decision juice at eight o'clock.
Marshall: Where is Barney going?
Ted: Yeah. We're not even in Manhattan anymore. Where's this girl live?
Robin: We're talking about a woman who's gotten Barney to commit. I'm guessing Narnia.
Lily: Wait, Barney, hold on. Where are you going?
Barney: Nowhere. *Pause* The beach. It's winter. Laser tag. Home. Shut up! You're going somewhere.