A rather difficult coordination exercise
for most people. If you've never heard of it before, try it. Rub your stomach
round and round with, say your left hand, and pat
your head up and down with your right hand ... at the same time. Try it now.
It's OK, I'll wait.
You see what I mean? Most people have some difficulty doing it, at least for a while. It's meant to show that our control of different parts of our body isn't quite as independent as you might naïvely think.
But there is hope. With practice, you can learn to do it quite easily.