8. Any Bright Light (Gremlins/Mogwai)
When Billy Peltzer receives a very unique pet from his Father Rand at Christmas, Rand passes on three golden rules that must be adhered to when looking after it, which were given to him by a boy in the shop he bought it from in Chinatown. The rules are to avoid getting the mogwai wet (which causes it to multiply), not to feed it after midnight (which causes it to mutate in to a horrible green creature known as a gremlin) and not to expose it to any bright light (as it is extremely painful to the creature - indeed sunlight will kill it). Inevitably, all of these rules are broken at some point, resulting in both mogwai and gremlins multiplying thanks to water, both mogwai and gremlins being hurt by bright light and, of course, the transformation in to gremlins thanks to the mogwai eating food after midnight. You know, I always wondered what would happen if a gremlin ate food after midnight...