For businesses, it’s an easy way to cash in.

Fast food has historically been a low-profit business with little customer loyalty.

So, chains unveil big giveaways, typically tied to their mobile apps, to help drive business and garner repeat customers.

**“National (insert food here) Days”** expand beyond doughnuts, including coffee, cheeseburgers, and ice cream, giving chains a boon in business and sparking publicity.

The 86-year-old tradition is celebrated on the first Friday in June.

It was started to honor the group’s **“donut lassies,”** who served treats and provided assistance to soldiers (the **“doughboys”**) on the front lines during World War I.

Doughnuts have been around since long before the First World War.

The Dutch would make **“olykoek,”** which translates to oily cake.

The first Dutch doughnuts didn’t have a hole, but they were fried in hot oil and the dough was sweet.

Dunkin’ has also partnered with the appropriately named singer **Jelly Roll** to celebrate the holiday with doughnut-themed merchandise.

It’s also selling a limited-edition doughnut-shaped sponge.

The chain is making it easy to celebrate: Any of its regular doughnuts, like glazed or cake, are free with no purchase necessary (limited-time Dolly Parton-themed treats are excluded).

Plus, it’s selling a dozen of its glazed doughnuts for just $2 with the purchase of a regularly priced dozen of doughnuts.

The convenience store and gas station chain with more than 700 locations is offering one free doughnut with a purchase of a coffee, with the deal lasting until Sunday.

The offer is only available in its app.

The chain, with more than 300 locations primarily in Texas, is giving out free glazed doughnuts with any purchase.

Existing members of the regional chain’s rewards program can get free **“Mexican Donut Bites”** on Friday on in-app and in-store purchases.

Members of its **7Rewards** loyalty program get to buy a glazed doughnut for $1 on Friday, with the offer also valid at Speedway and Stripes locations.