The sound comes from The Purge film series, where a loud danger alarm announces the start of the annual Purge, a twelve-hour period when all crime is legal. The films turned that siren into a cultural shorthand for lawlessness, and clips of it spread widely on TikTok, YouTube and gaming videos. Creators now use it far beyond horror, dropping it into pranks, challenges and reaction edits whenever they want a moment to feel suddenly dangerous, chaotic or darkly funny.