Arby’s has a special St. Patrick’s Day coupon on their website for their new Reuben sandwiches! Just click on this link and enter your name to get a buy one Reuben get one free coupon. It is only valid March 15th through March 17th. This offer is not valid with any other coupon or offer. There is a limit of one coupon per customer and is applicable with purchase of a Reuben or Double-Stacked Reuben sandwich.