Corporal Conroy needed to use a pay phone, but didn't have change for a dollar. He saw Private Duncan mopping the base's corridor floors, and asked him, "Soldier, do you have change for a dollar?"
Private Duncan replied, "Sure"
The Corporal turned red. He said, "That's no way to address a superior officer! Now let's try it again. Private, do you have change for a dollar?"
Private Duncan replied, "Sir! No, SIR!"