A piranha: it is boiling the water you’re swimming in and taking bites out of you

They don't chew: they bite, the meat goes straight into their stomach, and they bite again

Imagine a bulldog flattened with a meat tenderiser, shaved and sprinkled with glitter. Imagine more, and everywhere, or else: when I was a child, as sure as all cartoon sand would turn into quicksand, in every fictional body of fresh water swam very real fish with very real, sharp, tiny little teeth.

In The Simpsons, Millhouse is more worried about piranhas than that his mother will stop loving him. Bart is reduced to a skeleton by piranhas from a hosepipe.