The promotion is good on single-patty cheeseburgers at participating locations, while supplies last.
A Sonic Cheeseburger consists of a beef patty, American cheese, crinkle-cut pickles, chopped onions, shredded lettuce, and sliced tomatoes with your choice of mustard, mayo or ketchup. They normally cost about $3.50 (may vary).
They haven't indicated a duration for the offer so it could go on for quite a while.
Photo via Sonic.
