Super Slick Disposable Shorts and Tops
If you made plastic trash bag material thick enough to be worn, then you could make and hand out clothing to cover your body at every Water Park and then, everyone could shoot down the slide extra fast! You just make a few sizes of bottoms and tops or one size fits all. You take a cheap economical material (like a trash bag) make it thicker. Make clothes out of it and promote your Water Slide as twice as fast as any body elses' Water Slide.
Reward: Too see them at every Water Park.