The Joker means in slang: Batman 1 1940: The first appearance of Batman 1 405. His arch-nemesis is the Caped Crusader. He is known as the “Clown Prince Of Crime”. Although the real identity of The Joker is not known, Nicholson suggests that it could have been Jack Napier. There are different stories about the catalyst for his madness: He was a comedian who had failed before he was forced into crime by his unborn baby and wife. He was disguised as “Red Hood” and failed to steal money from Monarch Playing Cards. He ran from Batman and fell in a pool of waste by Ace Chemical Processing. It coloured his hair and skin green. He uses bizarre weapons such as static joy-buzzers and acid spilling flowers to amuse his victims, before they are murdered. He also uses bribery, terroism and other schemes. Harley Quin, a.k.a Harleen Quinzel is The Joker’s sidekick. Her love interest is accompanied by her in Gotham City. (in Slang Dictionary, added by Jaydon Costa)