NO SPOILING

Mother with her little son was visiting an exhibition of Army weapons. The son got interested in seeing an antiaircraft missile system. He asked the sergeant in charge of presentation: "What's this?"
"An AA missile."
"What's used for?"
"To shoot down planes."
"Oh," cried out the youngster, "do let me see you shoot down that plane!" and he pointed at a plane flying not far away from the place.
Addressing the sergeant the mother said severely: "Now, don't you shoot down that plane for him until he says 'please'!"