Yugster offers this Champion Men's Double Dry Boxer Briefs 6-Pack in Assorted Colors for $19.97. Coupon code "FREEYUGBUCK" drops it to $18.97. With $5 for shipping, that's $4 per brief and the lowest total price we could find for this quantity by $36. (Most retailers charge at least $10 per brief.) They're available in sizes M to XL.
Note: The countdown timer on the product page does not reflect an actual expiration time and resets daily.