Future Ted: [v.o.] Back when we were dating, Robin and I had this running joke. We were the only two people in the world who found it funny.
Barney: No way! March does not have 31 days.
Marshall: Yes, it does! Everyone knows that. It's like general knowledge.
Ted & Robin: [salute] General knowledge.
Future Ted: [v.o.] And we did it all the time.