Season 6: Episode 20 - The Exploding Meatball Sub

The Exploding Meatball Sub: Marshall finally quits his job at GNB and takes a volunteer position at an environmental organization. Lily tries to support this decision but eventually snaps, contemplating a whirlwind trip to Spain. After Zoey is able to get enough signatures for her petition to stop the building of the new GNB headquarters which would destroy an historical landmark, Ted realizes how difficult it is to be with a non-supportive partner. Meanwhile, Barney is distraught over Marshall's leaving GNB but while Robin is convinced it is an emotional response to abandonment issues, it turns out he is just angry he can not play a practical joke on him that he had been planning for months.