Robin: Ted's only teaching Barney horrible things about me.
Lily: I don't know. Check this out. This is actually kind of sweet.
[flashback to Ted's classroom:]
Ted: Now, we all know Robin's not what you'd call "touchy-feely." She doesn't say, "I love you," like a normal person. Instead, she'll laugh, shake her head, give you a little smile and say, "You're an idiot."
Barney: "You're an idiot"?
Ted: Yup. If she tells you you're an idiot, you're a lucky man. And if she does say "I love you," she's already broken up with you in her mind.