Once a year in Buñol, Spain, the streets run red—with tomato juice.

About 9000 people call the tiny town home. But each August, Buñol’s population temporarily swells to 200,000 as tourists from across the globe pack into its village square to pelt each other with tomatoes in the world’s largest annual organized food fight.

The event, La Tomatina, turned 70 years old this year—but no one quite knows how the popular food fight festival began. Some speculate that it started when some rogue townspeople attacked city councilmen with tomatoes at a festival. According to Vox, the Wall Street Journal added some credence to the myth in 1995 after they reported that La Tomatina most likely stemmed from a political tussle during a religious celebration.

The politicians probably didn’t like the food fight. But the townspeople apparently did, since the festival has been held every year since. According to the New York Times, La Tomatina grew into an international phenomenon in the 1980s thanks to the advent of Spanish national television. Today, the once-free festival sells entry tickets retailing for €10, and pictures and videos of pulp-stained participants flood the Internet in the days following the festival.

In 2015, La Tomatina festival was held on Wednesday, August 26, with visitors hailing from countries as far flung as England, Japan, India, and Australia. Plans are underway for 2016's festival scheduled for August 31—although it might be hard to top this year’s record-breaking 150 tons of fruit, which was imported in for the event. Yes, imported. The most bizarre fact about an already quirky festival? The town doesn’t even grow tomatoes.