This gets easier once a kid is old enough to drive (assuming he has a car). My kid's vehicle is basically a rolling gear closet / dumpster (and smells like the latter). I had to drive the boy's car the other day and got concerned because I was hearing a lot of rattling when I braked. Eventually I realized that he had about 20 baseballs loose in the back and every time I stopped or slowed they were rolling all over the place.