Stick a potato in a tailpipe and the back pressure will blow up the exhaust manifold!
I actually did this as a kid and it just pops out like cork.
Internet said shove it deep into the exhaust pipe with a broomstick.
When you do this it pops out just like a potato cannon.
Turns out that exploding gasoline is stronger than the friction of a slippery potato in a steel tube. Who'd have thought.
Real life Mecca Chameleon with notes to self