Cardboard Flap Catapult

I marched right up to the freshly delivered cardboard parcel sitting by the front shoe rack! One of its corrugated top flaps was folded back under tension, ready to snap. Naturally, I saw a spring-loaded springboard! I stepped onto the cardboard fold, testing the resistance with both feet. With a quick hop, I threw my weight down to compress the crease—and then sprang upward. Pop! The stiff cardboard flipped open with a loud thud, bouncing me forward into a pile of crumpled brown packing paper. I scrambled up covered in crinkles, grinning wide. Now that's what I call a solid lift-off!