The don't sink callout comes from the ground proximity warning system fitted to commercial aircraft, where it alerts pilots when altitude is being lost too soon after takeoff. Flight simulator players and aviation fans picked up the clipped warning because it is instantly recognisable even outside a cockpit, and short clips of it began circulating in plane-spotting and simulator edits. It remains popular because the phrase works both literally, for aviation content, and as a joke, for any moment when something is about to go badly wrong.