Why Do Drivers Drink Milk At The Indy 500

This weekend marks a huge milestone in American motorsports: it’s the 100th running of this country’s greatest spectacle of speed, the . And when it’s over, you’re going to see a lot of milk-chugging from the winner.

Tradition is everything at the Indy 500, and the winning driver downing a bottle of sweet, sweet victory-milk is one of the oldest and strangest. It started in the 1930s and became a race mainstay by the 1950s, although not every winning driver has done it—much to the chagrin of the crowd.

Where does this tradition come from? Why do people still do it? And what kind of milk do they drink? All of your questions will be answered in this explainer video.

Who’s going to down the milk this year?

Video Production & Animation: Elisa Solinas/Gawker