Ted: I don't get it, why won't Robin tell me why she hates malls?
Barney: Ted, you should be happy Robin has a secret. The more you learn about a person, the better chance you have of hitting the fatal 'oh' moment.
Marshall: The 'oh' moment?
Barney: Yeah, that moment when you find out that one detail about a person that is going to be a deal breaker.
[flashback to Barney talking to a woman at MacLaren's:]
Woman #1: It's a promise ring. I made a pact with God to stay a virgin till I'm married.
Barney: Oh. [leaves]
[flashback to Barney talking to another woman:]
Woman #2: I don't have an eating disorder. It's just when I put food in my mouth, I chew it and then I spit it out.
Barney: Oh. [exits]
[flashback to Barney talking to another woman:]
Woman #3: I just turned 30.
Barney: Oh. [exits]
[back:]
Barney: So, trust me, you want to postpone knowing anything about each other for as long as possible.