The tone comes from the Emergency Alert System used by broadcasters in the United States to interrupt programmes for weather warnings, civil emergencies, and regular system tests. Its distinctive attention signal was designed to be impossible to ignore, which is why it became familiar to anyone who watches television or listens to radio during severe weather. Online, creators began reusing short clips of the tone as shorthand for danger, disaster, or an urgent announcement, and it remains popular because that real-world association gives even a brief meme an immediate sense of seriousness.