The name is a play on the term fossil fuels and April Fools' Day.
Fossil Fools Day began in 2004 with coordinated actions across American and Canadian high schools and universities where they played over 125 coordinated April Fools' Day pranks centered around the dangers from using and harvesting fossil fuels.
[1][2] One prank included a mock oil spill in a public fountain.
Subsequent Fossil Fools Days have been held in many cities around the world, and are generally organized by one or more environmental organizations with funding from Energy Action Coalition and Rising Tide.
Protests may also encourage citizens to do their part with lifestyle changes such as riding bikes, reducing electricity usage, and investing in solar or wind energy for their homes.