"The Impractical Joker"
Joker puts Batman in his Human Key Duplicator, with a blank key that will be duplicated from his soon-to-be skeletonized body. His henchmen throw Robin in a Wax Spray Chamber, to be turned into a human wax sculpture.
"Is there any key to the solution of this monstrous scheme?"
Batman sneaks a key from his utility belt while Joker's men are chatting. He puts it in the gears moving the cutting blade, and the whole machine falls apart, releasing him. He fights the henchmen off, then takes a wax-covered Robin back to the Batcave, where a large dose of Bat Wax Solvent turns him back to normal.
Is Joker the master of time itself?