"The Funny Feline Felonies"
After being recommended for parole by Bruce Wayne, Joker walks out of the prison and is "kidnapped" by Catwoman. In truth, they are working together, trying to find a million pounds of gunpowder hidden somewhere in the city two hundred years ago by the famous crook Garçon Maltese. But to find the way to the treasure, they have to steal a certain nightshirt and a baby cradle that he left behind as clues.
While Batman and Robin are talking in Commissioner Gordon's office, Catwoman fires a bullet through a window from a hotel across the street. Everyone immediately drops to the floor. Batman pulls a small four-wheeled platform from under Gordon's desk, and puts it under his stomach, allowing him to easily wheel around the room while staying out of danger. He later calls this the "Bat-creep".