Fill a bowl with flour, and pack firmly. Empty the flour mound onto a large plate or small tray, so that it retains the shape of the bowl. Place an unwrapped chocolate bar (Herseys etc.) on the top. Players take turns using a knife to slice a part of the mound from top to bottom and slide it away from the rest (1/2 an inch is enough). Eventually one person will do it and the chocolate will fall into the pile of flour. The person must retrieve the chocolate with their teeth. Great fun.