Simpsons Season 9, Episode 18: This Little Wiggy

When Marge realizes that Ralph Wiggum has no friends, she volunteers Bart to be his friend. Initially unwilling, Bart discovers that Ralph's father, Officer Wiggum, owns a key that opens every lock in Springfield. The two go out at night and open many places to have fun, but soon encounter bullies Nelson Muntz, Dolph, Jimbo, and Kearney.