you have to take special classes to learn how to make it correctly, and you can only eat a little part, people like to do it because it leaves the tongue feeling weird, its still dangerous to eat though
All are poisonous and there are only certain parts you can eat. Only a professional should even think about preparing a puff fish for people to eat. If you're willing to take the risk, I hear it tastes pretty good.
Puffer fish have a highly toxic tetrodotoxin in some their organs. The filet is edible. Japanese chefs study for 4 years, just to prepare this stuff. If even a tiny amount gets on the edible part, it is usually fatal: there is no antidote. Yet the Japanese love to eat it. They call it Fugu. They say "I want to eat Fugu but I don't want to die" I saw a National Geographic special on it once.