Whataburger celebrates 74th birthday with free birthday cake flavored shakes

SAN ANTONIO (KTSA News) — Whataburger is celebrating their birthday but you get the gift.

The burger chain is turning 74 today and to celebrate, they’re offering a free 20 ounce birthday cake flavored milkshake.

To collect on the free frosty treat, you need to download the Whataburger app and create a rewards account, if you don’t already have one.

The special offer is available Thursday only but if you decide you like the birthday cake flavored shake, the chain says they are going to keep serving them up for a limited time.