Sonic: Half-Price Shakes All Day Long (10/11) October 11th, 2017 By Nicole Leave a Comment This post may contain affiliate links, which means I will make a small commission if you click and make a purchase.Thank you for supporting Cha-Ching on a Shoestring! To celebrate the kick-off of autumn, Sonic will be offering Half-Price Shakes all day long today (10/11)! There is no coupon needed to get this deal. (You may want to call your local Sonic to make sure they are participating before you head out). Yummy!