Comedy Club

The Comedy Club is a location in presumably Gotham City.

History
Allegedly, the man who would become the Joker had tried to do a stand up comedy routine to a bunch of people. However, his attempted joke went south, causing the present audience to voice their displeasure by jeering and throwing objects at him, some apparently including lethal objects such as hatchets. Eventually, the man, out of rage and terror, ended up fighting the men at the club and began viciously beating them. However, his troubles weren't over, as shortly after dealing with the patrons, he was then ambushed by some men (presumably those belonging to Carmine Falcone), and was then forced into acting as the Red Hood.

A year later, the man, now known as the Joker, relayed this event to his assigned shrink, Dr. Harleen Quinzel, shortly after his arrest and imprisonment at Blackgate Prison.

Trivia

 * The Comedy Club was a location that appeared during the Joker's therapy session with Dr. Harleen Quinzel at Blackgate Prison. Due to the Joker's tendency to change his backstory on a whim, it's unknown if this location actually existed.
 * The Comedy Club and Joker's fight with the displeased patrons is a reference to the Joker's alleged backstory in the influential one-shot comic story Batman: The Killing Joke by Alan Moore, where the Joker, before he became the Clown Prince of Crime, was a struggling comedian.
 * During the brawl at the Comedy Club, a song from the opera The Thieving Magpie is heard throughout the scene. This was a reference to the film A Clockwork Orange, which featured a similar scene where several escaped inmates from an insane asylum went to an abandoned theater and proceeded to fight Billy Boy's gang inside the premises.
 * The men who ambushed Joker at the club after the brawl from off-screen were never actually identified in the game or scene, but one of Joker's interview tapes where he relates to Professor Hugo Strange a similar story in Batman: Arkham City has him claiming that Carmine Falcone had forced Joker into participating as the Red Hood under the threat of killing him as well as ensuring his pregnant wife died, implying the men belonged to Falcone.