Reminder — Half Price Shakes at Sonic All Day Long This post may contain affiliate links. Please see my full disclosure policy for details. June 20, 2013 20 Jun Pin0Share0TweetGoogle+0shares Just a quick reminder that today, June 20th, Sonic Drive-Ins will offer 1/2 price shakes all day long! No coupon is required, just drive up and place your order to get yours! *Offer available at participating locations.