Steven Michael Johnson, best known as cancer-fighting T-shirt designer “Scuba Steve,” was arrested for allegedly impersonating a cop when authorities asked him to move his car at a local arts festival — but he claims it’s all a big “misunderstanding.” Johnson, who gained fame for founding Scuba Steve Clothing Company, was working as a vendor in downtown Picayune, Mississippi, at the Spring Street Festival on Saturday when a police officer asked him to move his car out of a restricted area. “He