It has been about a million degrees and ridiculously humid here recently, so we've had to spend a lot of our time indoors. However, kids don't do well cooped up for too long ... and I could tell that tempers were getting short and toys were getting boring, so I decided to let the kids wash my car one day.
This activity would have cost me pretty close to nothing, except I had to buy a hose and a few sponges. I filled a bucket with water and some dish soap, and let the kids go crazy. I think we were out there for an hour at least!
Please note, dish soap isn't the best thing to use for washing a car as it isn't really good for your paint. I personally am not concerned with the paint job on my car at all, and I figured dish soap would be easier on little hands than actual car soap. But please don't use it if you have an attachment to a nice, shiny, gleaming paint job.
I had totally forgotten how much fun a simple car wash could be!