Barney hopes a night out on the town will bring his conservative father out of his shell, but in the end he himself is worried his wild days have cost him his chance to settle down. Robin runs into a former crush, but when Ted realizes she was still dating him when they met, he does his best to prevent the two from recreating a spark. Lily and Marshall debate who would attract more attention in an open marriage and set out to see who can get five phone numbers the fastest while at a night club.