Half-Price Shakes All Day! This post contains affiliate links which means that we may be compensated if you click a link and make a purchase.. March 12, 2019 by Karen-Kupon Girl Leave a Comment Head on over to the Sonic Drive-In and score half-price shakes all day on March 13th, 2019! Limit to 5 Shakes at half-price per order! What is your favorite shake? Leave me a comment below, thanks! Karen – Kupon Girl A Grocery Budget List + Pantry Checklist Printable "We Respect Your Email Privacy"