In the episode where the "carnies" come to town and Homer and Bart get their booth taken away, and he lets them live with him. The Simpsons leave their house with the "carnies", and when they come back, their house is boarded up and locked. The man, Cooder, one of the carnies, is talking through the mail slot. A few scenes later, he is inside the house, but there is no mail slot on the door.