Sexnonagintillion comes from the naming system for very large numbers, where prefixes are combined to build names for powers of ten far beyond millions, billions and trillions. Because the word is rarely spoken aloud, a short clip that pronounces it cleanly is useful in its own right, and creators reuse it whenever a joke, quiz or comparison needs a number that sounds deliberately excessive. It does not rely on a catchphrase or a famous scene, so its appeal is the word itself: long, formal and oddly satisfying to hear completed in one breath.