Robin: But seriously, what other reason would Barney have to date Patrice?
Ted: It's an over-correction.
Robin: How dare you?! What is that?!
Ted: Barney was engaged to Quinn, a stripper he never really trusted. So he overcorrects by dating her opposite: warm and nurturing Patrice.
Lily: That does happen, like Ted. After you broke up with sweet innocent Victoria.
[flashback to Ted talking through the glass to a prison inmate:]
Ted: No, you hang up first.
Woman: No, you hang up first.
Ted: No, you hang up first.
Woman: Hang up, you little bitch!
[present:]
Lily: Over-correction.
Ted: Yeah.