A little hedgehog is fast asleep when all of a sudden, the light clicks on. He is NOT happy about being woken. "Turn off that light " he demands. The light switches off. And then on again. And off. And on. "Who keeps doing that? " The hedgehog bumbles around, exasperated, in a flurry of onomatopoeia -- GRRR OW CRUNCH. BANG -- as his room mysteriously goes from dark to light over and over and over again. It soon becomes clear that the cause...