This is most commonly used when a bus, train, boat, etc., reaches the terminal. It is a command that no one can remain on the vehicle. Bear in mind that for every kind of vehicle, one "gets on", then "gets off", EXCEPT for a car (or taxi), where one "gets into" and "gets out (of)". ,

Literally, "Every person who is ON - stop being on and get OFF!" :)

Everybody off! get off a vehicle, get off the stage, get out of the room Are they OK? To get off, you have to be on, first. You would not be on the room, you would be in the room. (so you'd say everybody OUT). So, yes, it works for every sentence where people are on :D Everybody off the inflatable banana!! Everybody off the bus!! Who rides an inflatable banana to work? I would, if I could hehehehe