Fruit ninja

The act of being a "fruit ninja" requires accelerating up to highway speeds, leaning out the window, and rolling fruit alongside the car. The idea, originally intended for just oranges, was that the centrifugal force of the juices and the pulp inside the orange presses outward on the peel, causing it to flatten out into a disk. Eventually, the peel can no longer take it, and it explodes. We figured we'd also try non-round fruit, for the heck of it.