'Of Course' - Season 5, Episode 17
After the gang learns that Robin deliberately set-up Barney with an incompatible self-help guru, they discover Robin hasn't been handling the break-up well.
Air Date: March 8th 2010.
Barney: I can't believe Robin's been so upset.
Marshall: I can't believe you threw up in your stormtrooper helmet.
Barney: I did something worse in it after the Phantom Menace premiere.
Barney: (After Marshall punches his stormtrooper helmet) Dude! Why did you do that?
Marshall: Because I'm angry at you! I'm angry at me, I'm angry at Ted, and frankly I'm still angry at the Empire.