The coupon can only be redeemed tomorrow, Wednesday, December 12, 2012. They're calling the event "Day of the Dozens!"
You can get the coupon on the Krispy Kreme Facebook here.
The promotion is a reward for a social media marketing campaign where Krispy Kreme challenged their fans to garner at least 12,000 Facebook "likes" in 12 days. Since the goal was surpassed, it means buy one, get one free donuts tomorrow!
The offer is only good at participating Krispy Kreme locations in the U.S. and Canada.