This deal has ended.
Update: the $20 discount appears to work for all colors on the landing page, though some have a base price higher than $21.90. Amazon has Crocs Blitzen Clogs for $21.90. Add two pairs of the "black/black" style to your cart and $20 will be subtracted, making it $23.80 for your total. These are well reviewed and still available in a number of sizes. Shipping is free with $25 and there's no sales tax (except KS, KY, ND, NY, WA).