Dunkin' began selling a limited-edition eagle cup nationwide for $10.99, with each purchase including a medium drink and only 20 cups stocked per location.
That scarcity helped drive immediate online demand, with Instagram and Reddit users posting store runs, missed-out stories and resale listings reaching about $50 on eBay.
The collectible is part of Dunkin's America 250 push, which also includes patriotic drinks, doughnuts and Munchkins under its "Star-Spangled Sips and Summer Flavors" lineup.
Social media is central to the rollout: Dunkin' said shoppers had already spotted the cup online before stores, and one Instagram post about it drew 21,000 likes and more than 400 comments.