Free large drink with purchase of any burger at regular menu price. Redemption Instructions Log in to view the redemption instructions for this offer. Participating locations include: SONIC 509 N Ed Carey Dr Harlingen, TX 78550 Phone: 956-423-5283 Map SONIC 1302 Morgan Blvd Harlingen, TX 78550 Phone: 956-428-5598 Map Sharing Options Share Offer Copy Link