Chick-fil-A is offering free food to customers who dress up like cows

It's Cow Appreciation Day and Chik-fil-A is offering free food. But there's a small catch.

Chick-fil-A is giving out free food to customers on Tuesday in honor of its 13th annual Cow Appreciation Day promotion.

But there’s a catch: Customers who want the free food must come to their Chick-fil-A location dressed up like a cow.

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Customers who don some kind of cow-related clothing or accessories can get a free entree — that includes the Spicy Chicken biscuit for breakfast and a variety of chicken sandwiches and chicken nuggets throughout the day, among other options — any time between the store’s opening and 7 p.m.

Children who wear cow-related clothing will get a free kids meal as well.

The fast-food chain, known for its chicken sandwiches, has long used a cow touting a “Eat More Chickin'” sign. But customers won’t need to dress head-to-toe in a cow costume as seen in the commercials — any kind of cow apparel will work, the company says.

Last year, more than 1.6 million customers participated in the event, the company said.

However, the fast-food chain isn’t the only company offering deals on July 11. As usual, 7-Eleven is selling free Slurpees at participating locations (since the date is 7/11). And Amazon’s massive Prime Day sale began July 10 at 9 p.m. and runs throughout July 11.

This story originally appeared on Fortune.com