"Satisfaction" begins its musical and lyrical assault on the senses with what can be called, with little argument, the most iconic guitar riff of 1960s rock. What's most remarkable is that Keith Richards literally wrote that intro in his sleep. "I woke up in the middle of the night. There was a cassette recorder next to the bed and an acoustic guitar," he told Rolling Stone about putting his slumber-derived inspiration down on tape. "The next morning when I woke up, the tape had gone all the way to the end. So I ran it back, and there's like 30 seonds of this riff -- 'Da-da da-da-da, I can't get no satisfaction' -- and the rest of the tape is me snoring!"