1.  "Paranoid", Black Sabbath.   Bassist Geezer Butler claims it was thrown together merely as a "three-minute filler for the album."

  2.  "Sweet Child O' Mine", Guns N' RosesSlash says the riff came together in five minutes, and the rest of the song followed.

 3.  "Yesterday", The BeatlesPaul McCartney says he woke up one day with the song in his head, and immediately started working it out on the piano.  He did spend a good amount of time writing the lyrics, though.
 4. "Rock 'N' Roll", Led Zeppelin.  It was written in 15 minutes, after drummer John Bonham launched into the intro for Little Richard's "Keep a Knockin'".

 5.  "Cherry Pie", WarrantJani Lane wrote it in just under 15 minutes, after being asked to produce a more "radio-friendly" hit.  But he HATED it.  In 2006, he said, quote, "I had no intention of writing that song . . . 

 6.  "Life on Mars?", David Bowie.  He says he wrote it in one afternoon. 

7. "My Sharona", The Knack.  Guitarist Berton Averre had been kicking the riff around for years, but singer Doug Fieger insisted that the rest was written in under 15 minutes.

8."Under Pressure", Queen & David Bowie.  They supposedly wrote it in one night . . . although some say the classic bass line was added later.

9. "(I Can't Get No) Satisfaction", The Rolling StonesKeith Richards laid down the hook on a bedside tape recorder just before falling asleep.