Sonic – 1/2 Price Cheese Burgers July 29th The links in the post below may be affiliate links. Read the Full DisclosureJuly 28, 2015 by Kim Julian Sonic Drive-In is offering 1/2 Priced Cheese Burgers all day July 29th. *Limit 5. Mention the Facebook post when ordering. For more bargains check out the Restaurant Deals Page!