Sonic Deal: Buy One, Get One Free Master Blast 03/27/2014 by Ritu M. FTM may earn a small commission via affiliate links in this post. Read our full disclosure policy here. Today only, Buy any Master Blast at SONIC, get one free all day on March 27th. Bring a friend (because it’s not cool to cheers yourself). Other Posts You Might Like:Philly Pretzel Factory: FREE Pretzel On 4/26!3 Months of Amazon Music Unlimited for FreeFree 30-Day Trial Of Amazon Prime + Free 2-Day Shipping2023 Veterans Day Free Meals and DealsFree M&M's Delivered to Your Door on Halloween