In 1970, the group was under contract to Decca. They decided it was time to leave and create their own label-free from corporate meddling and restrictions. They gave Decca that last song and they continued touring.
They honored their contract with Decca by recording the now-infamous “Schoolboy Blues.” The song was too profane for Decca to release, so they buried it — they thought. In 1983, the controversial song was accidentally included in a four-LP box set titled The Rest of the Best and released in Germany.
The 1970 song by The Rolling Stones, commonly recognized by the name "Cocksucker Blues". The song is based on Dr. John's "The Lonesome Guitar Strangler", released on his 1969 album Babylon. It was written and played by Mick Jagger to be the Stones' final single for Decca Records. The Stones were leaving Decca and starting their own record label, but Decca claimed they were owed one more single under the band's current contract. The Stones thence delivered this song, with its context and language chosen specifically to anger Decca executives (there are explicit references to fellatio, anal sex and bestiality in the lyrics). Decca refused to issue the song as part of an album.
This oversight probably cost someone their job. The records were pulled from shelves. and the set was reissued without “Schoolboy Blues.” Now, thanks to the Internet, the censored song is a YouTube sensation.
If you’ve not heard the Stones’ “Schoolboy Blues,” originally titled “Cocksucker Blues,” it is as near as your Smartphone or laptop. How offensive are the lyrics? Go here to read.
https://www.youtube.com/watch?v=tdyE08eHfQQ pt 2
https://www.youtube.com/watch?v=sKMp-xznNgo pt1
With "Schoolboy Blues" the Rolling Stones apparently took a cue from Phil Spector, who in 1963 wrote and had the Crystals record "(Let's Dance) The Screw" as a parting shot at Lester Sill, his former partner at Philles Records, with whom Spector had had a falling-out. (A persistent myth is that "The Screw" was also meant to technically fulfill the terms of a contract, but Sill has denied this).