Quote from Robin in Bagpipes
Ted: Oh, good. There you are. You'll tell me the truth. Barney says that you two never fight. Robin: Oh! I guess that's true. Barney: Told you. Ted: No way. I love you both, but you are the two most emotionally ill-equipped individuals in the history of relationships. You two must have had at least one fight. Robin: You know what? We did. Ted: Aha! Robin: Mmm-hmm. There was one small dispute about which one of us was more awesome. We just called it a tie and had sex.