One of the ways we could tell a Technical Instructor was nearby, was from the sound of the metal heel taps they wore on their boots. A sudden tap, tap, tap as they strode along the barracks was a real attention getter for we recruits.
However one fellow in our flight learned how to imitate that sound by simply snapping his fingers. No one knew it until one evening after lights out, when everyone is supposed to be in bed, except the person on guard duty.
Several guys were in the shower area, shining their shoes, breaking the rules to avoid breaking the rules for not having them properly polished. The person on guard duty also happened to be the same guy who could imitate a TI with the click of his thumb and middle finger.
The guard decided to walk past the showed area, snapping his fingers. The sound echoed through out the barracks and guys scattered left and right, rushing to make it back to their beds before the instructor busted them.
At least one guy busted a toe in the stampede.