When the Beatles first began, Paul McCartney and John Lennon wrote songs in close collaboration, often sitting face-to-face as they worked out ideas. They worked together so closely, in fact, that they each learned how to play guitar upside down.
It's common for left-handed guitarists to play right-handed instruments — but most people, like Jimi Hendrix, re-string the guitar so that it's properly configured for lefties.
Not the left-handed McCartney and the right-handed Lennon, however. On the latest episode of McCartney: A Life in Lyrics on iHeartPodcasts, the artist recalled how he and his collaborator would trade instruments during writing sessions: "I was used to turning [guitars] upside down because I worked with John a lot, so I had to grab his guitar. I could play upside down and so could he."
This came in handy during the writing of "Yesterday" (which is the subject of the podcast episode). When he wrote the lyrics (having already thought of the melody in a dream), he was travelling across Portugal en route to the apartment of his friend Bruce Welch (of the instrumental rock band the Shadows). When he arrived, he borrowed Welch's right-handed guitar and played him "Yesterday" — the first time he ever performed the song for another person.
Of course, that song went on to become the most-covered song ever — even though some famous singers were too "macho" for its vulnerable lyrics.
Hear the episode below.