Sonic 1/2 Price Shakes All Day ThursdayYou’ll love the current Hot Deals, sorry you missed this deal. Celebrate the official start of summer and treat yourself to a 1/2 Price Shake All Day at Sonic on Thursday, June 19. Plus, many Sonic Drive-Ins are offering 1/2 Price Shakes everyday after 8 pm through the summer! Check with your local SONIC Drive-In for participation.