Buy One, Get One FREE Hot Dogs at Sonic, Today (7/17) Only! July 17, 2014 by Rebekah The links in the post below may be affiliate links. Read the full disclosure.Print Email Today, July 17th you can score Buy One, Get One FREE 6″ Hot Dogs at Sonic! Just make sure to mention the offer when placing your order. Please note that add-ons and additional toppings will cost extra.