The self-satisfied doors originate in Douglas Adams' The Hitchhiker's Guide to the Galaxy, where doors are programmed to express genuine pleasure at opening for people. The joke appears across the radio series, novels and screen adaptations, becoming one of Adams' most quoted background gags. Clips of the sighing door circulate online among science fiction fans who use it to mock overly helpful technology. Its staying power comes from that perfect blend of British absurdity and relatable annoyance at cheerful automation.