If the walrus was Paul, John was the mule. John Lennon claimed he was the Beatle who typically carried the band's stash of diet pills in the early years, when the group needed artificial stimulation to get through long nights of multiple sets in the clubs of Hamburg, Germany.

Lennon once joked that he was his own inspiration for the 1966 song 'Dr. Robert,' which predated such better-known Beatles drug references as 'A Day in the Life' ("I'd love to turn you on") and the perennially debatable intentions of 'Lucy in the Sky With Diamonds.' "If you're down, he'll pick you up, Dr. Robert," Lennon sang. "Take a drink from his special cup, Dr. Robert."

When the song appeared on the UK version of 'Revolver' in the summer of 1966 (in America, it was on the 'Yesterday and Today' album), many swinging Londoners figured the real Dr. Robert had to be gallery owner Robert Fraser. Fraser, who was friends with all the Beatles and the Rolling Stones and helped advance the careers of Pop artists like Peter Blake and Andy Warhol, was a bon vivant known as "Groovy Bob" for his endless supply of mind-altering substances.

Some speculated that Dr. Robert was actually Bob Dylan, who had introduced the Beatles to the joys of smoking pot in the summer of 1964. A few knew that Lennon and George Harrison, along with John's wife, Cynthia, and George's girlfriend Pattie Boyd had been slipped their first hits of LSD in cups of coffee by an acquaintance, a dentist named John Riley. The more literate among them might have suspected that 'Dr. Robert' came from a character of the same name in the last novel of noted LSD advocate Aldous Huxley.

In fact, 'Dr. Robert' was about none of the above, or maybe a little of each. The real Doctor Feelgood was most likely Dr. Robert Freymann, a Manhattan physician known to New York's artists and well-to-do for his vitamin B-12 injections, which also featured liberal doses of amphetamine. Freymann, who signed Charlie Parker's death certificate in 1955 (estimating the saxophonist's addiction-ravaged 34-year-old body to be between 50 and 60), bragged that he could rattle off 100 names of his celebrity patients (reportedly included Jackie Kennedy) in 10 minutes.

"The song was a joke about this fellow who cured everyone of everything with all these pills and tranquilizers," Paul McCartney once said. "He just kept New York high." Not surprisingly, Freymann eventually lost his license to practice medicine.

The mischievous Lennon was apparently pleased to write his first song that was, in no uncertain terms, about drugs. He "seemed beside himself with glee over the prospect of millions of record buyers innocently singing along," as one lifelong friend would claim.