Find a place to hide that is out of the line of sight of all surrounding NPC's, and save the game. Then, pick up an item by pressing [Z], and drag it to your hiding spot. Once it says you are "hidden", press [E] to add it to your inventory. If you lose any Karma, reload your saved game, and try again. A good place to do this trick at is Gloria Van Graff's energy weapons shop in Silver Rush, Freeside. You can do this with any of the items on the counter, and there is a hiding spot on the back side of the room.