 When the two began working on a song that Stefani stated was too personal , she left to visit Kanal . He played her a track on which he had been working and which became " Crash " , the album 's final single . The two tried to write new material , but gave up after two weeks . They did not return to work until six months later , when Stefani began collaborating with other artists , commenting , " If I were to write the chorus of ' Yesterday ' by the Beatles , and that 's all I wrote , that would be good enough to be part of that history . " Stefani resumed work with Linda Perry , who invited Dallas Austin , and many other artists , including Outkast 's André 3000 , the Neptunes , and Dr. Dre . Stefani announced the album 's release in early 2004 , marketing it as a " dance record " and a " guilty pleasure " . 
