Has anyone noticed that the black cabs of London have squeaky breaks? OK, How about me having the great idea to fill an old pop bottle with left over paint and attach it upside down to the rear of the old truck I made from bits of wood and pram wheels and then sit on it and run down the hill as you pull the stopper out. My idea was to draw a nice white line down the pavement, just like on the roads. As I speeded up the line became more a series of gloopy dots and was less than straight, On reaching the bottom and applying my break, I found it was impossible to reach back and put the stopper in. The result was painted hand, and a very messy footway for which I got a good telling off. I just don't see the problem myself, it could have been artwork today!
Then there was the time when I decided to see how fast my tricycle would go down the same hill, but On engaging the break, which was only on the front wheel, I very quickly found myself on my back with the tricycle upside down on top of me and a large cut in the back of my head.
I can think of lots of other misadventures as well, but I never fell out of a tree or broke a bone, so one has to be grateful. Brian