The biggest hoax ever?
Our government believed that the financial world would crash because computers couldn't handle the year changing to 2000. I had tears in my eyes when I received a written demand from the FAA requiring me to sign a document indicating that my company was complying.
The government was terrified that our banks would all fail. But think about it for a second: how many thirty-year mortgages had they written in the previous twenty-nine years? Probably millions of them, each amortized through 2001 without exception. If stupidity was a star, this would be a whole galaxy.
Heat index
Likely one of the biggest hoaxes ever: if the temperature is 35 but your meteorologist says the index is 30, only an idiot would feel an urgent need to add antifreeze to the car.