The joke serves as a metaphor for the relationship between Batman and the Joker : both are "mad," but they can never truly help or trust each other to "cross over" to sanity. Production Fact: The Bathroom Dance
This "joke" was intentionally dark and inappropriate for the show, reflecting Arthur's view that comedy is subjective and that "everyone is awful these days". The "Flashlight" Joke ( The Killing Joke , 1988/2016)
This is arguably the most famous Joker joke, appearing at the end of the graphic novel and its animated adaptation .