S05E23 - The First Halloween Ever
Synopsis
A long long time ago, people were afraid of the ghosts and goblins that live in the forest, so when a young man and his wife get lost, they are very afraid, but they get fed up being scared so they turn the tables on the ghost and goblins by putting on spooky costumes and scaring them right back. Except the ghosts and goblins they scare are really the villagers who've come looking for their friends, and in the end, they all decide they've found a wonderful new tradition: dressing up and saying... Boo!