Foster's Home for Imaginary Friends (2004)

S5E10 Nightmare on Wilson Way

What begins as a harmless joke spirals into chaos when Bloo finds himself fleeing from a horde of zombies. As the situation escalates, he must navigate a series of terrifying encounters while trying to figure out how to escape the nightmare he inadvertently created. With the undead hot on his heels, Bloo discovers that facing his fears is the only way to survive this unexpected horror.