https://shakeshack.com/national-regional-offers#/?t=17675448666 Chicken Shack or Chicken Shack Lettuce Wrap (max savings of $9.99) for Free with a Purchase of $10 or more when you apply promo code CHICKENSUNDAY at checkout via the Shake Shack Mobile App, online, or in a restaurant at a kiosk on Sundays through June 28, 2026. Select free pick up where available, otherwise, delivery fees will apply.