The name was suggested by Ginn’s brother, artist Raymond Pettibon, who also designed the band’s logo: a stylized black flag represented as four black bars. Pettibon stated “If a white flag means surrender, a black flag represents anarchy.” Their new name was reminiscent of the anarchist symbol, the insect spray of the same name, and of the British heavy metal group Black Sabbath, one of Ginn’s favorite bands. Ginn suggested that he was “comfortable with all the implications of the name.” The band spray painted the simple, striking logo all over Los Angeles, gaining attention from potential supporters, and thoroughly irritating police. Pettibon also created much of their cover artwork.

via Wikipedia