You can have your donuts and your coffee too and March 21, 2007 is Free Iced Coffee Day. This freebie is a 16 oz cup of the signature double brewed and then iced coffee at Dunkin' Donuts. Iced coffee is the biggest seller at the franchise - right behind hot coffee. If you've never tried iced coffee, this is your chance. Check it out. You may discover that you enjoy your cup of Joe cold.