The Amazing World of Gumball (2011)

S1E25 The Poltergeist

Richard suspects a ghost is haunting the attic, but it turns out to be Mr. Robinson, whom Gumball placed there after he fell into a catatonic state following his wife's departure. While Gumball and Darwin focus on finding a way to revive Mr. Robinson, Richard, oblivious to the truth, busies himself setting up traps to catch the supposed ghost.