The title is actually the second episode of Season 10 for the sitcom Two and a Half Men , not Adventure Time (whose S10E2 is titled "Always BMO Closing").
Walden is a mess after his marriage proposal to Zoey fails spectacularly, involving fireworks and Michael Bolton. [S10E2] A Big Bag of Dog
In a manic attempt to fill the emotional void, Walden goes out and buys a massive, expensive dog—the titular "bag of dog." The title is actually the second episode of
Walden's erratic behavior starts causing major tension with his business partner, Billy (Patton Oswalt). Billy (Patton Oswalt).