Yesterday we went to a birthday party where they had this massive bounce-house-meets-water-slide.
Our hosts informed us that you can pick one up for $300-400. This seems like a hefty investment until you realize that renting a bounce-slide for the day is almost the same price. And, if you rent yours out to friends for, say $50 a day, you can easily make back what you spent in one summer.
This water slide kept the kids busy all day and exhausted them to the point that they were all docile by the time the adult party got started. Because it's not strictly a bounce house, tiny-tot Ikaika could safely have fun at the same time as the big kids (with close supervision). It was almost impossible to get him out but eventually he had to pee and climbed out on his own.
Why in the world he thought he needed to get out to pee when his diaper was soaking wet anyway I will never know...but I appreciated the effort.