When I was an infantry platoon commander, my Marines trained regularly for nighttime reconnaissance patrol. As we moved along, each of us would whisper the name of any obstacle to the person behind so that no one would be surprised and utter a cry that would disclose our position.

During one exercise, the lead man in the formation occasionally turned around and whispered to me “Log” or “Rock,” which I would pass along. Suddenly there was a crash ahead of me and, from several feet down, I heard a single whispered word—”Hole.”
— Mike Robbins