What can you do with a hill, a large sheet of plastic and baby oil?
CREATE A LARGE SLIP AND SLIDE!
Spread out your plastic on a hill – if rectangular, the length should go down the hill. Then pour/spray baby oil all over that plastic. Our sheet was 10×25 and we used six bottles of baby oil. We probably could have gotten away with four bottles but as you see the kids were fully clothed (in what they consider “junk” clothes) and the clothes soaked up so much of the baby oil. If they were in bathing suits it would have worked much better with fewer bottles. We also had them wear helmets just because they tend to try extreme things – better safe than sorry.