Two or three aliens who have evolved radial symmetry (and therefore have no "front") gather around a human. They take turns tapping it on the shoulder to get its attention one after the other. They have fun watching the human spin around to face each of them after every new tap, immediately followed by the next, and the next. The human could just hold still, or walk away, but it's very frustrating, and the compelling urge to tell someone to stop can't be done while their back is to them. And thus, the game continues.










