He'll just sleep with all the Dynamo Girls and our games would be the target of terrorist acts from The Joker.
The Joker has been known for his evil deeds like paralyzing Batgirl, killing Robin, poisoning the city's water supply, and destroying a Lamborghini, however, even he's respectful and would never hold somebody hostage for money or to trade. He merely wants to have some fun while setting the world afire. He has morals!