The Marine drill instructor was to escort new recruits to the mess hall. After everyone had made it through the chow line, he sat them down and told them, "There are three rules in this mess hall: Shut up! Eat up! Get up!"
Checking to see that he had everyone's attention, he asked, "What is the first rule?"
Much to the amusement of the other instructors, 60 privates yelled in unison, "Shut up, Drill Sergeant!"