In 1965, John Lennon, George Harrison, Cynthia Lennon, and Pattie Boyd were having dinner at a dentist friend's house. The dentist put LSD in their coffee without telling them first. When he revealed what he had done, John was pissed off, and rightly so. "How dare you fucking do this to us?" he said. Rolling Stone's Mikal Gilmore has the story and an animated interview with John about their first trip on LSD and the secret history of Revolver:
"It was as if we suddenly found ourselves in the middle of a horror film," Cynthia Lennon said. "The room seemed to get bigger and bigger." The Beatles and their wives fled Riley's home in Harrison's Mini Cooper. (According to Bury, John and George had earlier indicated a willingness to take LSD if they didn't know beforehand that it was being administered.) The Lennons and Harrisons went to Leicester Square's Ad Lib club. In the elevator, they succumbed momentarily to panic. "We all thought there was a fire in the lift," Lennon told Rolling Stone in 1971. "It was just a little red light, and we were all screaming, all hot and hysterical." Once inside at a table, something like reverie began to take hold instead. As Harrison told Rolling Stone, "I had such an overwhelming feeling of well-being, that there was a God, and I could see him in every blade of grass. It was like gaining hundreds of years of experience in 12 hours."
The couples ended up at the Harrisons' home in Esher, outside London. John later said, "God, it was just terrifying, but it was fantastic. George's house seemed to be just like a big submarine... It seemed to float above his wall, which was 18 foot, and I was driving it. I did some drawings at the time, of four faces saying, 'We all agree with you.' I was pretty stoned for a month or two." This unwitting initiation into LSD would find its fulfillment the following year in Revolver, the Beatles' bravest and most innovative album.
"Beatles' Acid Test: How LSD Opened the Door to 'Revolver'" (Rolling Stone)