"Do you have any kangaroo costumes?" you ask.
"Sure do." replies the clerk as he takes to to a rack with several one-piece kangaroo costumes, their big feet trailing on the floor. You notice one with with a pouch (which contains optional boxing gloves). "I'll take this one. The pouch will be useful for carrying stuff."
The clerk looks like he's about to say something but instead he just smiles. "Certainly, Sir. Just remember to remove all your clothes before putting it on.".
Later that night you stand naked in your room, admiring the roo costume before putting it on. After you have put the attached head on and done up the zipper on the back, you start to feel a tingling passing through your body. Even though you've wearing a costume, you feel the carpet under your feet, even more of it than you should. Wriggling your toes, you discover that the costume's big feet are now yours! It's not a costume, you've a real kangaroo now!