Pretty dumb. These kids ‘round here buy kits to tap into their exhaust manifolds that will dump used motor oil into the exhaust in order to make the diesel smoke.
Your post reminds me of the guys in the late 50s that would rig a spark plug (or some spark device) near the end of each dual exhaust pipe - stomp the pedal to send through some unburned fuel - and light them off trying to get a bang and a flash. Seemed really dumb at the time.
