Kamp Krusty - S4-E1
Trivia: At the end of the show, the person singing 'South of the Border' is actually creator Matt Groening. Confirmed on DVD Commentary.
Kamp Krusty - S4-E1
Trivia: James L. Brooks, the executive producer, was so enthusiastic about the episode's premise that he wanted to make it the official Simpsons movie. This idea was abandoned because the writers had problems getting the story to 23 minutes, let alone 90 minutes.
Answer: Willy referred to an encounter he believed he had with actual aliens, while Wiggum thought he was referring to the arcade game.