In the small town of Buñol, Spain, it’s not just the unsavory musician that’s targeted by flying tomatoes. During the last week of every August, twenty thousand produce-wielding participants from across the globe gather in the plaza to paint the town—and one another—red. Part of a weeklong festival honoring the town’s patron saints, La Tomatina is the biggest (and likely most acidic) food fight in the world.

Before the tomato slinging can commence, a small fleet of trucks lug more than 100 tons of overripe tomatoes into the center of town. According to tradition, the fight can’t begin until a participant clambers up a heavily-greased, two-story-high pole to claim a ham perched at the top. However, performing such a feat typically takes far too long for those in attendance, and tomatoes are flung long before the ham has been snatched. Unavoidably messy and intensely red, the fight lasts for about an hour. After the last tomato has fallen, fire trucks arrive to spray down the town, and a few lucky tomato-drenched fighters get hosed down by friendly residents.

Though no one knows the true origin story of La Tomatina, there are countless theories. Some believe the initial Tomatina occurred when a few residents flung food from a truck spill, while others believe it began as a tomato-based act of rebellion amongst disgruntled townspeople under Francisco Franco’s rule. One of the more popular legends claims that it began when two local farmers got into a squabble: Words were exchanged, tomatoes were tossed, and soon the whole town joined in.

Despite its small beginnings, La Tomatina has grown into a huge deal for the town of Buñol. Though the fight lasts only an hour, the festival lasts nearly a week, with parades, music, dancing, and a recently added tomato-themed obstacle course. These squishy battlegrounds are a now prime destination, however, and participants have to purchase tickets in advance to claim a spot amidst the soaring tomatoes.