Pepsi says hamburgers are #BetterWithPepsi—and you can get a free one is on them.

Friday, May 28, is National Hamburger Day, and Pepsi is betting you will enjoy it more if it's paired with an ice-cold Pepsi. To test their theory, the soft drink maker is offering a free Pepsi to anyone that posts a picture enjoying a hamburger and a Pepsi on National Hamburger Day. It doesn’t matter where you get your hamburger or if the restaurant offers Pepsi products, Pepsi will reimburse you for it.

Why National Hamburger Day? PepsiCo took third-party surveys that revealed 60% of people preferred Pepsi to Coke when eating a hamburger. Participants were given hamburgers from McDonald’s, Burger King, and Wendy’s along with blind samples of Pepsi and Coke. More than half of the participants said their burgers tasted better with Pepsi.

PepsiCo’s corporate executive research chef for global beverages, Chef Kyle Shadix, says there is actually a scientific reason behind the preference.

“The signature flavor and bright citrus blend of Pepsi cuts through the fat and gives a juicy hamburger a fresh, clean and delightful taste,” said Chef Kyle. “It’s just like how adding a touch of citrus in cooking can heighten flavor and change a food or beverage’s entire flavor profile, which is why it is used by chefs and mixologists across the world to add brightness and lift the flavors of the foods and beverages they create. This is why Pepsi is a no-brainer to pair with burgers.”

Courtesy of PepsiCo

To get your free Pepsi on National Hamburger Day, simply snap an image of yourself with a hamburger and a Pepsi, then post it to Twitter, Instagram, or Facebook with the hashtag #BetterWithPepsi. Pepsi will contact you via social media and issue a digital rebate for up to $3.49. Can’t post a picture? Just click on a #BetterWithPepsi ad on Facebook or Instagram, and share your receipt.