Japanese name for the blowfish or pufferfish, a small fishie which inflates itself with water to erect little spikes on its surface and look bigger than it actually is to scare off predators. Of course, humans aren't so easily fooled.

That's why the fugu is also absolute (really about 57%) deadly poison, which accounts for it being the rarest, most expensive (and suicidal, in this noder's opinion) variety of sushi.