"Blue" is the title song from Joni Mitchell's 1971 album of the same name. There has been persistent speculation that the song is about fellow songwriter David Blue, who was a friend and possible love interest of Mitchell's when the album was released. She has denied the connection.
The lines "acid, booze and ass, needles guns and grass, lots of laughs" from Blue were sampled for a bonus track on Mac Dre's Genie of the Lamp album. The song is sampled on the track "My World Is..", from Blu and Exile's 2007 album Below the Heavens. The track is also sampled on "Catch My Drift", a 1989 song by the British group A.R. Kane.