A moon roof nigger is a person who smokes marijuana with his friend in a car during the rain with the
windows open, then asks his
friends to put the windows up so the rain does not come in; but in order to let the smoke out of the car he decides to open the moon roof of his car which contradicts the action of closing the
windows to keep the rain from coming in. This person acted like a nigger therefore this person is described as a being a Moon roof nigger.