We used to call those military-style shirt-to-socks clip-on elastic thingies "slingshots." Why? Well, every once in a while, on the parade ground, you'd hear the muffled "snap" of one of them letting go (from the sock end) and then a muffled whimper from the poor guy who just got "snapped" in a very delicate place. BTW - even for the guys who used them, they were for full-dress uniforms only, not for high-activity times.