During Marine basic training at Parris Island, S.C., the drill instructor threw a pine cone among the recruits and yelled, "Grenade!" The trainees immediately
turned away and hit the ground. "Just as I suspected," chided the drill instructor. "Not a hero among you. Didn't anyone want to jump on that grenade to save the others?"

A little later the DI again threw another pine cone. This time, all the recruits but Mike jumped on the "grenade." "Why," demanded the instructor, "are you still standing there?"

"Sir," Mike replied, "someone had to live to tell about it."

(from http://www.sermonfodder.com)