During a simulated attack, the troops have to defend themselves against an imaginary enemy, as the sergeant calls it. Bawling out orders, he notices that one recruit shows little response.
“You there,” the sergeant shouts, “the imaginary enemy is advancing, and you are caught in the crossfire. Action!”
The recruit takes two steps to one side.
“What are you doing, man?” the sergeant yells, purple with fury.
“I’m taking shelter behind an imaginary tree, Sergeant,” answers the recruit calmly.