Every August, the small town of Bunol, Spain, spends one hour pelting itself with roughly 145,000 kilograms of overripe tomatoes, and the cobblestones come out cleaner than they were before. This episode traces how the world’s largest sanctioned food fight began in August 1945 when a parade participant dropped his giant papier-mache head, flew into a rage, and started hurling produce from a market stall, and how a group of young locals brought their own tomatoes the following year to do it again on purpose.

We follow the festival through its ban under Francisco Franco’s dictatorship, the arrests of participants, and the 1957 mock tomato funeral with a marching band and a coffin that shamed the authorities into lifting the ban. Then we look at the television report that made it famous, the 2002 designation as a fiesta of international tourist interest, the 2013 shift to a ticketed event capped at 20,000 people, and the safety rules, pre-fight greased pole ritual, cleanup chemistry, and global copycat festivals that followed.

• Why the Palo de Jabon greased-pole climb for a ham must end before the trucks roll in
• Where the low-quality tomatoes come from and why they are grown just for throwing
• The squash-before-you-throw rule and other rules of engagement
• How tomato acid leaves the streets and whitewashed walls brighter than before
• Copycat events from Colorado to China, and why India banned commercial tomato fights over food waste