Sonic BOGO Free Master Blast March 27This free event has ended, but find upcoming FreebiEvents here. Visit your local Sonic on Thursday, March 27 and enjoy BOGO Free Sonic Blast all day. Which is your favorite blend? I love Cookie Dough. Plus, don’t forget about 1/2 price drinks from 2-4 pm daily! Check with your local SONIC Drive-In for participation.