THAT is why Robin can't keep his hands off of Batgirl.
The Joker kidnaps Batman's fiance. Why? Because he's a madman, bored, and hornier than ever. He ceases the opportunity to snatch her from his nemesis and holds her hostage in his lounge only to end up tearing her clothes off and satisfying himself with her holes. But when Batman gets drugged and kidnapped as well, it's up to Robin and Batgirl to untangle the mystery. Suddenly Robin can't seem to hold himself back and forces himself on Batman, who, turns out, is the one that seduced Robin in the first place.
Joker's friend and long-time accomplice Harley Quinn didn't take too late to the fact that The Joker was getting his rocks off, and without her! Without any confrontation she throws herself into the fuck fest and enjoy a little of The Joker and Batman's finance. Harley Quinn just wants what's best for The Joker, but also wants a piece of the action. Girls and attention...
Catwoman finally "captured" by Batman and Robin, now forced to do their bidding and abide by their outrageous demands. Catwoman has been a bad bad girl, and that pussy is going to get pounded.