When Storm was much younger he would hang upside down from one of the holes in his cat tree. I called it doing the monkey. All I had to do was to go to the cat tree and pound on it with my hands and say "Do the monkey". Then he'd jump up and hang upside down. My other cat at the time,Pepper, tried to do it a few times but he wasn't very coordinated and so he'd just fall to the floor. I have some pictures of Storm doing this but they're on my other computer.