National hamburger day, celebrated every year on May 28, is the perfect excuse for burger lovers to indulge in their favorite comfort food while cashing in on some irresistible deals. Falling right at the start of the summer grilling season, this unofficial holiday invites foodies to either fire up their own grills or hit up their favorite burger chains to enjoy mouthwatering discounts and freebies. With food holidays becoming a fun trend among fast food enthusiasts, national