What Is Life? (S01E15)

After Jake pulls the greatest prank in the history of pranks, Finn decides to get back at him by building a "Never-Ending Pie Throwing Robot" (NEPTR). But when Finn steals some of the Ice King's lightning power to make NEPTR fully operational, he gets caught up in a paternal struggle with his arch nemesis over the naively innocent pie-throwing robot. (iTunes)