Shake Shack is offering a buy one, get one promotion on all classic and featured shakes, available weekdays from 2 to 5 p.m. through the end of August.

Here’s how it works:

• Open the Shack App or head to shakeshack.com to place an order
• Add two shakes to your cart
• Make sure your order is scheduled for a weekday (M-F) 2-5PM at your local Shack
• Use code SHAKEUP at checkout