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, "No, SIR!"