On a construction site once, the guys would either grind up styrafoam or saw dust and put it in the defroster vents. When the defroster went on it looked like it snowed in the car, or they would also tie a clip of .22 blanks we used for the concrete fastener to their exhaust manifolds, about a quarter of a mile would do it, rapid fire explosions!! They would be on the side of the road looking under the hood and we would drive by laughing our asses off.
