Just watch the fire hydrant spray something at you in 3-D! Simple, but pretty cool! The thing it sprays changes every day! Press space to increase the flow, and hold the mouse at the same time to further increase it! But, the supply isn't enough to support the highest level for long, so it will come in spurts.
I got the general idea in a sudden burst of imagination while looking at a car racing game that was in 3D, but otherwise, it's totally original!