You want flames?
With a carbureted engine, while driving the car at speed, in gear, shut off the engine and floor the throttle. The engine will continue to turn (driven by the gearbox), and the intake will suck fuel and air through the carburetor, but there will be no spark because the ignition is switched off. A few cycles will see your exhaust system filled with unburned fuel and air in the perfect mixture. Then turn the key back on and
BANG!!!!!!!!!!!!
The results can be quite impressive, up to and including a completely exploded exhaust system. I've only done it once, in a Shelby GT350 clone (before I was smart enough to know the result of such experimentation), and the explosion sent a fireball out from the bottom of the car and burned two black circles on the pavement. It's a testament to the strength of Flowmaster mufflers that they didn't explode.
Needless to say, I would recommend trying this with utmost caution, if at all!