According to The Theory of Everything Else: A Voyage Into the World of the Weird by Dan Schreiber—yes, the lengths we go to find things that may be of some moderate interest—when the remaining Beatles were producing “Free As a Bird”:
“. . .it was suggested that what they should do is add some ukulele music at the end.”
While the ukulele is generally associated with Hawaiian music thanks to the support of King Kalakaua, the last king and second-to-last monarch of Hawaii (following his death in San Francisco in 1891 he was succeeded by Princess Lydia Kamakaeha, who became Queen Liliuokalani, who was deposed in 1893 in a coup that included support of the U.S. military), it was invented in Portugal, but like a staple of Hawaiian breakfasts—Portuguese sausage—the musical creation of what was once a major seafaring nation established itself there as deeply and as thoroughly as the meat concoction.
But I digress.
Schreiber goes on to write that the Beatles decided to do something at the end that they’d done on earlier recordings (e.g., “Revolution 9”) when they were fully the Beatles: adding backmasking to the track. Backmasking is the method in which something is recorded backward and then, when played forward, reveals a message.
“. . .the message they ended up using was a snippet of Lennon saying, ‘Turned out nice again.’ This turned out to be a perfect line to put over the ukelele as it was the catchphrase of musician and ukulele player George Formby.”
And now cue the “dun-dun-dun” sound of something that is about to be shockingly revealed.
After backmasking the phrase, when it was played back
“. . .it didn’t produce a garbled sentence as expected. Instead, what everyone heard was the voice of John Lennon, though a backward record, saying the words ‘Made by John Lennon.’”