The clerk, identified only as Angelica, said a man who had rolled up to the drive-thru window after ordering coffee asked her to change a $100, which she declined to do.
That's when the man told the employee she was being robbed and began climbing out of his truck and into the drive-thru window.
Angelica says she tried to close the window, but the man's arm was in the way.
The man immediately took off toward his truck, leaving Angelica behind to seal the incident with a catchphrase: "I said, 'Go run on Dunkin'.'"
Police are still on the lookout for the suspect, who was last seen driving away in a white Ford Explorer.