Spiegel Online has the word on "Clean Monday," an awesomely misnamed festival that marks the transition from Carnival to Lent each year in the Greek seaside town of Galaxidi:
Preparations for the war--also known as alevromoutzouromata or "people throw flour at each other"--are intense. Locals dye bag upon bag of flour with food coloring and paint their faces with charcoal. Authorities cover historical buildings with plastic tarps so they are not damaged by the clouds of dyed flour. And revelers, at least those who know what they are in for, bust out goggles to protect their eyes from the flying starch
Afterwards, there is hardly a carnival-goer not covered from head to toe in flour. Many jump into the sea to wash off--prior to a long evening out in the town's tavernas.
It's official: flour is the new tomato, and we're booking a trip to Greece this Spring!