When can I say other person to "off"?
"Off" here is a shortened version of "get off," which is an expression said when passengers need to depart from some kind of vehicle. You can use "off" when somebody needs to get off a car, train, or boat. Ex: Everybody off the bus. Ex: Let's get off the train. You can also use "out" in the same way. This is a shortened version of "get out." Ex: Get out the car! Ex: Out the car.