The Slip 'n Slide is synonymous with summer. A simple idea that spawned decades of backyard fun, the toy consists of a long sheet of plastic that is laid over grass and leads into a small wading pool of water. The whole thing is wet down with a hose and often some dish soap, forming a kind of landing strip. With a running start, children (and even the occasional adult) slide down the strip on their stomachs and splash headfirst into the pool. Created by Wham-O in 1961, the Slip 'n Slide is still hugely popular — and an economical choice for those who don't have space for a pool.