Paul McCartney reveals how a 'happy' teen hitchhiking trip with George Harrison delivered a shock

Paul McCartney shared a humorous memory from his teenage years with fellow Beatle George Harrison involving an electric milk truck - and an unfortunate shock.

The 83-year-old musician said the experience later inspired part of a song featured on his upcoming album "The Boys of Dungeon Lane," which is scheduled for release later this month.

"Those were the only vehicles we knew that were electric, [and this one] went about four miles an hour," McCartney said. "But it was a lift, so we were quite happy."

George Harrison ended up sitting directly on top of the battery.

Everything appeared normal until Harrison's jeans accidentally made contact with part of the battery through a zipper on his back pocket.

"Bang! He jumps up," McCartney recalled, yelling, 'Ahhh!'"

Turns out "the battery gave him a bolt."

McCartney said Harrison later showed him the result of the "bolt." The incident left Harrison with what looked like "a great big zip tattooed into his bum."

The Beatles star also recalled recently speaking with Harrison's widow, Olivia Harrison, about the story.

McCartney said she remembered hearing the story differently and believed that he - McCartney - had been the one shocked, not Harrison.

"I think it's amazing the way memory does that. It can just morph," he said.

The guitarist and songwriter was a member of The Beatles alongside McCartney, John Lennon and Ringo Starr.