Caribou Coffee Coupon: Buy One Get One FREE on Memorial DayMay 27, 2012 This post may contain a link to an affiliate. See my disclosure policy for more information. This Memorial Day, May 28th, Caribou Coffee is offering buy one get one FREE drinks! You can either print out the coupon, or show it to the cashier on your phone. Limit one offer per person.What’s your favorite drink at Caribou?