this is a simulation of a trampoline. The space bar is the equivalent of applying downward pressure onto the trampoline. Now there's an X-velocity for sideways movement with the space bar.
Please love it!!!
Note: You have to press the green flag twice. Also, in order to eliminate those weird gray lines, play it in java.In the Flash Player you can get rid of the gray lines by right-clicking and choosing Quality > Low. You can also make art with the lines. I think that's more fun. Thanx!