"Has anyone you don't know asked you to take anything on the plane for them" This is a common question at a check in desk in airports, it is to check that everything in your bag is yours and that there is not anything that you do not own in your bag, examples: stolen goods, drugs, alcohol. It may be easier to understand as. 'Are you carrying anything that is not yours or the possession of someone you know'

Officer: "Has anyone, whom you don't know, asked you to take anything on board the plane for them ?" - Passenger: "No"