Fast food chain Whataburger is celebrating National Hamburger Day by giving away one year's worth of free Whataburger items to 75 lucky customers.

How to enter

Customers who purchase Whatameal menu items 1-8 on May 28 (National Hamburger Day) will be entered for a chance to win when they order online or scan the Whataburger app in-store.

Seventy-five people will be chosen for the grand prize of free Whataburger items for a year. Winners can redeem one free item per order, with a total of five items available per month. The entire reward is worth $480 over 12 months.

The select free items include a Whatachick'n meal, Whataburger meal, Whatawings, one breakfast item and a small milkshake.

The promotion is in honor of the burger chain's 75th anniversary this year. It first opened its doors on August 8, 1950, in Corpus Christi, Texas.