Robin: Okay, you and me, that's insane. If you even thought about it for one second...
Barney: But I have thought about it for three seconds, and it makes a lot of sense. We both think the marriage commitment thing's a drag. We both want something casual and fun. And we clearly get along really well.
Robin: Wow, that actually did make a lot of sense. But what about Ted?
Barney: I checked with Ted.
[flashback:]
Barney: [on the phone] Hey, Ted, so now that things with you and Victoria are going pretty well, I assume you're probably over all the girls you were into before, right? I take your silence as a yes, so, ergo, therefore, say I were to hook up with someone, say, I don't know, Robin, you'd be cool with that, right?
Ted: Sure. Good luck with that.
[back:]
Barney: Totally gave us his blessing.