A bean burrito from taco bell

Another fanny pack

Surely his weapons.

Small dead animals to reward Joker with should the need arise.

chloroform

The secrets of the universe.

His list for Lady Ann, his super clever voice lines, his will to live, his car parts/mechanic tools, who knows really?

Maybe a Gameboy Advance with Super Mario World. For when he's not in your party.

Joker keeps his cat in a bag. Morgana keeps his cat in his fanny pack. Morgana's cat has another cat in its fanny pack. Morgana's cat's cat has another cat in its fanny pack. Morgana's cat's cat's cat has another cat in its fanny pack. Morgana's cat's cat's cat's cat has another cat in its fanny pack. Morgana's cat's cat's cat's cat's cat has a river in a desert in its fanny pack. Mystery solved.

Shit...