Bugs Bunny seems to be able to pull just about anything he needs out of his butt.
Unless they changed the name, you mean a Robe of useful items. For Many Things, you want a deck of cards.
I did mean the other, yes.
RPG: Toon, by Steve Jackson Games, let people keep things in their Back Pockets.
Game: The Thing Your Aunt Gave You But You Don’t Know What It Is: Hitchhiker’s Guide To The Galaxy.
My backpack and/or jacket in middle to high school. I once fit an entire N64, game libraries, controllers, and fight stick in a standard jean jacket, and nobody could tell. Other times, it had ferrets in it. The backpack could be trusted to have pretty much anything in it, from an adjustable wrench to a soldering iron to a textbook to a class I wasn’t taking, to, one memorable day, a vacuum tube. I still have no idea how that got in there.
Douwe Dabbert and his magic knapsack, but he seems to be almost unknown outside the Dutch-speaking countries.