Every Sunday til Dec 15, 2024, Shake Shack is offering FREE Chicken Shack Sandwich with any order of $10+ for a limited time. To get the discount, adding Chicken Shack Sandwich to your order in your mobile app, online, or in-store kiosk and use the coupon code: CHICKENSUNDAY at checkout. One time use per order. Max savings of up to $9.79.