(CNN) — Each August, around 20,000 people head to the tiny Valencian town of Bunol, Spain for the La Tomatina festival -- an excuse to hurl 170 tons of ripe tomato slop at one another.
Well, the origins are obscure.
Some say it started when a spat broke out beside a vegetable stall in the 1940s.
What's certain is that it's the world's biggest food fight and a major tourist draw.
To ensure it doesn't turn into "Attack of the Killer Tomatoes!" there are strict rules in place.
No throwing tomatoes that aren't squashed and no throwing anything that isn't a tomato.
There's no dress code, but old T-shirts, perhaps accessorized with goggles seem to be the thing.
The booze is advertised as cheap -- probably even cheaper if the order's a Bloody Mary.