Robin: Why is Ted teaching a class about me?
Marshall: It all started a few weeks ago.
[flashback to Ted and Barney talking at MacLaren's:]
Barney: ...rather than rolling around next to some eyeliner in Robin's purse. Stinson out! [leaves but turns right back] Stinson back in. Say, hypothetically, I did want to change who I am to become a better boyfriend to Robin, which I do not! What kind of changes are we talking about?
Ted: Why, I mean, there's just so much you need to know about her. Okay, for starters, don't ever cry in front her.
Barney: Okay.
Ted: And whatever you do, don't cry in front of her four times.