This sound comes from a classroom joke rather than a famous film or viral video. According to the uploader, it was taken from an engineering class instructions video, where students kept skipping ahead to the moment the instructor said rectangle. That repeated skipping turned a single ordinary word into a shared in-joke, and the clip has since been kept as a tiny, easily replayed reaction sound. Its appeal is not fame but familiarity: the drier the delivery, the funnier the interruption feels.