Deadly Meal..

Everyone are taught since young that you can't just pluck any mushroom you see in the woods as it might be poisonous and deadly. Even though a Blowfish (Fufu) may look really cute and delicious in the sea, you still need a licensed chef to prepare it for you, simple because it's 1200 times more toxic then cyanide.

However, there are some food out there, though commonly eaten by us, contains toxic that may cause harm when it's not prepared properly. Here's a list of 5 I've found on the net..

1. Potatoes.
   Potatoes contain glycoalkaloids (solanine and chaconine). Cooking at high temperatures mostly removes the toxin, although headaches, diarrhea, and cramps—and in severe cases, coma and death—can occur in rare cases. Ever wonder why we’re told to keep potatoes away from light? It’s to prevent higher concentrations of solanine. So don’t eat potatoes after they have turned green.
2. Tomato.
   Although the fruit itself is safe (more technically a berry), tomato plants contain glycoalkaloids, which are indeed toxic.
3. Chocolate.
   Chocolate contains the alkaloid theobromine, which in unusually high doses can be toxic to humans. However, it would take an unholy amount of chocolate to achieve this. But other species react much worse: dogs, parrots, horses, and cats can be killed by ingesting chocolate.
4. Tapioca.
   Tapioca, if not processed properly, can be toxic. It contains a natural source of cyanide, whose precursor, linamarin, is rendered harmless if properly dried, soaked, and baked.
5. Shellfish.
   Shellfish poisoning is mostly associated with mussels, clams, oysters, and scallops. These shellfish are filter feeders and can accumulate high levels of toxics including domoic acid, produced by microscopic algae. Cooking doesn’t always inactivate these toxins and some can lead to death in high dosages.

(source)