Summer Soltice promotion, Sonic is offering half-price milkshakes for the Winter Soltice which is tomorrow, Friday, December 21, and the longest night of the year.
You have to mention the offer when ordering to take advantage of it though.
Seems like a pretty good opportunity as any to try out the new Chocolate Mint Holiday Shake. It's a little bit cold to be eating/drinking ice cream for me, but I know some people who love ice cream during the winter.
Sonic's shakes are available in Chocolate Mint (limited-time only), Vanilla, Chocolate, Strawberry, Pineapple, Banana, and Caramel.
The offer is good at participating locations only.