A fiasco is a disaster. It's not a natural disaster — like an earthquake or a volcano; a fiasco is usually the result of human failure.
Fiasco comes from the Italian term that means "to make a bottle." How it came to describe an utter, embarrassing, disaster in the English language is still unknown. Today, you'll hear fiasco used in situations that have gone so horribly awry that they are almost laughable, like the Thanksgiving dinner fiasco in which the turkey burnt to a crisp, the dog ate all the side dishes, and everyone had to eat frozen pizza instead.