The site is in German, but it is relatively easy to figure out. Select the game "Home Run 2004".
You just move your mouse over the guy to keep him from falling (you don't have to click, just move). Obviously, if the guy is leaning left, you move the mouse to the right and vice versa. Oh, and you can't see your mouse, so that makes things a little more difficult. Have fun!
www.wagenschenke.ch/