Celebrate St. Patrick's Day with a half-price shake at Sonic!   This offer is valid today only (3/17) at participating locations. You don't need to print a coupon - enjoy! Thanks, For The Mommas! Sonic Half-Price Shakes (Today!) was first posted on March 17, 2015 at 2:15 pm. ©2008-14 Deal Seeking Mom™. All rights reserved. Use [...]