Ted and Robin are flustered to find out their upstairs neighbors are always having sex...err bagpipes as future Ted calls it. Ted goes upstairs to discover they're old and can't tell them to stop, cause, hey, good for them!
Meanwhile, Barney reveals that he's never had a fight with Robin and convinces Marshall to stand up to Lily and stop cleaning up the dishes after himself. Using an elaborate speech and a horribly misogynistic dream sequence in which he makes out with Lily, the plan sounds pretty good to us too. Marshall goes for it, completely butchers the speech (would it have mattered anyway?), and ends up in a multi-day fight with Lily.
With tactics like that, Ted is convinces there's no way Robin and Barney aren't fighting. Inspired by his own bagpiping problem, Ted finds out from Barney's downstairs neighbor that the two are fighting all the time. Apparently everything worked with Barney's "walk out of the room" and Robin's "get naked" strategies until they were trapped on a ski lift where neither could employ their trick. After that, the fight snowballed into every problem they've ever had. They eventually come to Lily and Marshall for advice and soon our favorite married couple realize how small their problems are, make up, and celebrate with some champagne that they're still the best couple. Oh and they do a little bagpiping too.
Don't worry, Ted and Robin work it out, but just have to deal with the fact that maybe not everything is a competition. They don't have to be the best couple...