Delta Is Celebrating National Cheeseburger Day With Free Shake Shack by Michal Addady @FortuneMagazine September 15, 2016, 3:45 PM EDT E-mail Tweet Facebook Linkedin Share icons This story has been corrected. See below. Delta Air Lines dal fliers have a delicious surprise coming this week. Customers who are traveling from John F. Kennedy Airport in New York to Los Angeles’s LAX on Sunday will get a free Shake Shack shak burger, according to The Verge. The promotion celebrates National Cheeseburger Day by handing out Shake Shack vouchers to all Delta customers traveling from JFK to LAX on Sept. 18. You can redeem your coupon for one free ShackBurger at the Shake Shack location in West Hollywood, which just opened up this past spring. It was the New York-based chain’s first outpost to open up on the West Coast, competing with Los Angeles favorite, In-N-Out—which even Shake Shack CEO Randy Garutti admits he loves. This offer comes as part of a larger partnership between Delta and Union Square Hospitality Group. The company curates many in-flight menus for Delta One fliers. CEO Danny Meyer is also the founder of Shake Shack. A previous version of this story stated that coupons would only be handed out to Delta One customers on select flights. All customers traveling from JFK to LAX on Sunday, Sept. 18 will receive a coupon.