What is the purpose of this sentence?
lock the door on your way out
a. to ask a question
b. to make a statement
c. to give an order
d. to express a feeling

On your way out" means "as you go out/leave the room, or the building". Most often this would mean that you should lock the door after you have gone out of the building and shut the door behind you. So "lock the door on your way out" really means "Lock the door immediately after you have left the room/building". Which can definitely be considered as giving an order.

just say it's your friend did it and you had no idea?