The line comes from the automated announcements heard on New York City MTA buses, where riders are routinely reminded to use the rear door when getting off to keep boarding moving. Taken out of that everyday transit context, the clip began circulating as a short soundboard sound for memes and edits, often used as a dry dismissal. Its appeal has lasted because almost anyone who has ridden a city bus recognises the voice and the routine, so the joke lands instantly without needing any setup or explanation.