When it comes to summertime treats, milkshakes hit the sweet spot—a cool, comfort food classic to beat the summer heat, served with a side of nostalgia. Wayback Burgers announced that it will celebrate the official start of summer by giving away one free Junior Black & White Milkshake per guest its locations nationwide on Monday, June 20, no purchase necessary.

Wayback Burgers’ milkshakes are made the old-fashioned way by hand, using only fresh milk and hand-dipped ice cream. Its classic Black & White Milkshake is made with premium vanilla bean ice cream, fresh milk, and a blend of vanilla and Hershey’s chocolate syrup. Guests are encouraged to share their shakes using the hashtag #FreeShakeDay on Twitter or Instagram, and leave a comment on Wayback Burgers’ Facebook page.

“Our annual Free Shake Day is a tradition that Wayback Burgers is excited to bring back each year,” says John Eucalitto, president of Wayback Burgers. “Wayback Burgers was modeled off of the traditional roadside burger joint, where people gathered to enjoy great burgers, milkshakes, and company, and this special brings back that feeling of quintessential Americana. We cannot think of a better or tastier way to celebrate summer’s official arrival.”