A sergeant was passing the barracks after lights out, when he heard some voices from inside. He slammed open the door, and shouted: Listen, you guys! A few minutes ago, you all heard me say good night. What you must realize, is that when I say "Good Night," what I really mean is "Shut up!!!"
The room instantly fell silent. But after a few seconds, a small voice could be heard from somewhere in the far back of the dark room: "Good Night, Sergeant"