OKLAHOMA CITY--(BUSINESS WIRE)--SONIC® Drive-In (NASDAQ: SONC) is bringing back the popular and refreshing line up of Slush Headquarters(SM) flavors for another summer of fun, adding even more candy-inspired flavors to the mix, with help from brand ambassador and NBA All Star, Kevin Durant. More flavorful and sippable than a snow cone, SONIC’s icy treats are flooding the drive-in with 28 different options made with real fruit, exciting flavors and real candy including Nerds®, Jolly Ranchers® an