The Great Money Caper - S12-E7
Continuity mistake: When they are driving home Marge starts to moan at the children to quiet down. In this shot she has no lipstick. In the next shot from outside the car she has lipstick on and has it for the rest of the scene.
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.