To take advantage of the offer, you'll need to show the barcode from their website here (you can also find a list of participating locations on the same page).
You can choose from either two dozen Original Glazed donuts or one dozen Original Glazed donuts and one dozen assorted donuts, while supplies last at participating locations. There's a limited of two redemptions (that's four dozen donuts) at the discounted price per customer.
The regular price for a dozen Original Glazed donuts at my nearest Krispy Kreme shop is $11.99, while an assorted dozen is $12.99.
Photo via Krispy Kreme.