The Springy Stopper

I set off down that long corridor runway, and right near the skirting board, something coiled caught my eye! It was a shiny metal spring sticking straight out from the wall with a white rubber cap on the tip. I gave the tip an eager tap with my knuckles, and spro-o-oing! It whipped back and forth like a wild pendulum! The buzzing vibration tickled right through my fingers. I braced both feet, pressed the cap all the way back against the baseboard, and let go—the snap filled the whole quiet hall. Now that's the snappiest little gadget I've tested yet!