The line comes from Pixar's 2008 animated film WALL-E, set aboard the Axiom starliner where humans live in a sterile, automated environment. When WALL-E returns covered in Earth dirt and carrying a plant, the ship's scanners trigger a foreign contaminant warning and a cleanup response. Online, the official sounding alert was clipped for soundboards and meme edits because its serious tone clashes with trivial messes. It remains popular for cleaning fails, germ jokes and reveals of anything that clearly does not belong.