If you've not heard of Sporthocker before, don't worry - the trick is to look as foolish as possible, all while juggling a stool around and pretending its a skateboard. Then you sit on it. Yes, really. Those crazy Germans.
It's too difficult to explain how you "play" it, if that's the accurate verb to describe this strange, strange sport. Just watch the video below, and tell me you can last the whole way through without laughing your pants off. [Sporthocker via Inventor Spot via OhGizmo]