Barney: You can keep going out with her, but you're gonna regret it. One time, I met a girl at this very bar. I saw that she had the crazy eyes but I ignored it. And then, sure enough.
[flashback:]
Lauren: Barney, can I ask you a question?
Barney: Anything.
Lauren: Would you like to have a threesome?
Barney: Of course.
Lauren: Great. It'll be you, me and Mr. Weasels. [holds up stuffed animal]
[present:]
Ted: So, did you do it?
Barney: No. It ended up being just a twosome with the third one watching from a chair.
Ted: Which one were you?
Barney: I'd rather not say.