Last year one of the girls in the office bought an advent calendar from the nearby supermarket. After she had left the office that evening a colleague and I managed to carefully open the box at the bottom, slide out the tray that contained the chocolates and remove them from the packet. We replaced the tray, sealed up the box and put the calendar back on the wall. It was a laugh to see the look of disappontment on her face when she realised on about the 4th door that the box contained no chocolate. What really made our day was her taking off up to the supermarket to complain and get a replacement.