Contractual Obligation

(I got the backstory on this one from Dr. Demento)

In 1970, the Rolling Stones were under contractual obligation to provide Decca with another single.

Mick Jagger figured that "Cocksucker Blues" (RealAudio link) would get them out of their contract without any risk of the single actually being released to radio stations.

He was right.

The great part is that it's a damn good song; Jagger manages to make his voice sound uncannily like a plaintive harmonica. The Stones knew their blues, and there's something in the simple and raw profanity of "Cocksucker Blues" that gets right to the heart of the blues.

Rarely has a record label been told to go fuck itself more literally or with more style.