After the jump.
Ted’s telling the story of the only fight he’s ever been in. It all starts when there’s a new bartender at MacLaren’s, Doug. Doug gives the group free drinks, Doug doesn’t let anyone else sit in their booth, Doug is awesome. [Doug hates lawyers. Poor Marshall.]
And then one night they all come into the bar and there are some stockbrokers sitting in their booth. Doug’s not there, and the stockbrokers refuse to leave, so Ted and company are forced to sit elsewhere – until Doug shows up and gives the intruders a talking to. Ecstatic, he tells everyone the booth is theirs again – they’ve just got to fight for it first.
The guys debate what they want to do – Marshall is adamant that he won’t fight, Ted ultimately decides to go for it because he’s never been in a fight, and Barney’s in when Robin says fighting’s hot. [Lily tries to tell him that's not a good enough reason, but obviously it's good enough for him.] By the time they get outside, Doug has already knocked out all three stockbrokers, but in his frenzied state, he doesn’t realize he did it alone.
Barney and Ted go ahead and take the credit – and exchange blows to make it look more convincing. [I imagine this is Barney's idea, as he later milks his war wounds for all they're worth when he's talking to Robin.] Of course, the truth about who fought and who didn’t has to come out, and eventually we hear the story of the only REAL fight Ted’s ever been in.
And filling in a blank in past spoilers – Robin didn’t quit her job in Japan, she was fired. Apparently not, according to the episode that just aired! And that, kids, is why we always remember that episode sides are subject to change.