Fill up your lead character's backpack and make sure the sixth item is anything but a Club. Select the Use command, select Equip, choose any blank spot in the menu and press B. The screen will flash and the last item in the leader's backpack will change into something else. (If you did put a Club there, it will vanish.) You can repeat the code to change it to something else. The game cycles through these items in a definite order, but once it reaches the Club, it will always vanish on the next try.
Taken with permission from Flying Omelette.