Dunkin Donuts is offering a free doughnut with any beverage purchase on Friday at locations nationwide, the doughnut chain said in a news release. Buy a dozen doughnuts at Krispy Kreme on Friday and score a dozen glazed for $2 at participating locations.

National Donut Day also celebrates the Salvation Army "Lassies," or women who served doughnuts to soldiers during WWI. National Donut Day is on Friday, June 6, and several chains are offering deals for the annual unofficial food holiday.

The last Friday in June marks the unofficial holiday National Donut Day. The celebration was started by The Salvation Army in 1938 to honor the women who traveled to France during World War I to deliver donuts and other snacks to soldiers. They were known as Donut Lassies and Donut Girls, the organization said in a press release.