This clip comes from Stanley Kubrick's war film Full Metal Jacket, released in 1987. Online, short drill instructor lines from the movie became popular because their harsh delivery fits reaction edits and callout jokes. This particular quote is often used when a video suddenly reveals something confusing, ugly or ridiculous. It keeps circulating in meme culture because the line is brief, recognizable and easy to place over freeze frames, zooms and abrupt cuts without needing extra context.