While racing your engine or just driving down the highway, turn the ignition off then on again. You'll hear one or more loud explosions. Bystanders will think they're being shot at. Possibly your muffler will be destroyed.
This works with gasoline engines.
How it works:
When you turn the key off, the sparkplugs no longer fire. So that perfect gas-air mixture your car was running on gets pumped into your exhaust system. Then when you turn the key back on the sparkplugs fire and the hot exhaust detonates the rich mixture in your exhaust system like a huge potato cannon.
I did it with an old pickup with no catalytic converter. With a catalytic converter things might be different, but you know what? I'm not going to test it.
If your car has been running for long enough to heat up the catalytic converter it will probably burn the fuel-air mix before too much builds up. If the converter is cold it might act as a spark arrestor. Either way might result in a smaller volume detonating at once. And any damage is likely to be more expensive.
This fun new trick has cost me $90 so far.