March 17, 2014 No Comments Half-Price Cheeseburgers at Sonic Drive-In Today In honor of St. Patrick’s Day, Sonic Drive-In is offering 1/2 Price Cheeseburgers all day today, March 17th. Half-Price Cheeseburgers at Sonic Drive-In Today – EXPIRED Facebook Twitter Add Comment Notify me of follow-up comments by email. Notify me of new posts by email.