The toilet paper we buy now comes in individually-wrapped (paper wrapping) rolls, and several rolls in every box are wrapped in bright red paper. Those rolls have the suggestion printed on them that you put them towards the bottom of the pile in the bathroom so that when you reach for a new roll and the one you pull out is wrapped in red paper, you know it's time to go get more from the box. It's a clever design, although it does somewhat rely on people remembering to order the rolls that way when putting them in the cabinet...