Put a ‘Not for Sale’, ‘Do not call 123-456-7890’ sign.
I remember seeing a late 60s Camaro with a “Not For Sale” sign in the window. I guess the owner got tired of people coming to the door trying to buy it.
A while back I saw a news report about a car with a “Free Car” sign on it and the keys inside. Someone drove away with it and later found a dead body in the trunk.