In the episode where Arthur turns 75, Doug takes him to a diner/restaurant to get him out of the house while Carrie sets up for his suprise party. Arthur and Doug are sitting at a table in the restaurant discussing what to order. In the beginning of this scene there is an upside-down cup over a saucer next to Arthur and no cup at all by Doug. Then the cup jumps across the table and is next to Doug, then Arthur, then Doug, then the cup is right-side up then upside-down with no saucer. This continues throughout this entire scene and stops once they finally order their food.