Arby’s: FREE Roast Beef Sandwich w/Drink PurchaseJune 5, 2011 This post may contain a link to an affiliate. See my disclosure policy for more information. Sign up for an Arby’s Extras Rewards account, and you’ll get a FREE roast beef sandwich with the purchase of a drink! This coupon will be sent to you via email. You’ll also be signing up to receive discounts and promos via email.