Shake Shack is offering a FREE Single Shake Shack Burger with any purchase their new BBQ Burger or Boneless Rib Sandwich for a limited time. To get the discount, adding Single Shake Shack Burger and BBQ Burger or Boneless Rib Sandwich to your order in your mobile app, online, or in-store kiosk and use the coupon code: BONUSBURGER at checkout. One time use per order. Max savings of up to $8.49. Offer ends June 17, 2026.