It's on the Revolver album. John Lennon sings it: "And your bird can sing." On one level, it's perhaps not a remarkable work of art. It's just another Beatles love song, with John complaining that his girlfriend is obsessed with this and that, and when she decides to wake up an smell the coffee, he'll be 'round.
The thing of it is, nobody knows this song, few people have even heard it. What really boggles the mind is, this song is melodic, complex, has a story, is catchy. It's the kind of song that is so good, so memorable, that any other popular music combo of the sixties would have been happy to hang their hats on it as their "one hit wonder". Yet, since its' the Beatles, nobody has even heard of it because it hides behind many dozens of gems of popular music that are engraved on the memories of millions of people. Eleanor Rigby, She loves you, here comes the Sun, I want to hold your hand, please stop me or I will be typing all day.
Give it a listen sometime. If you listen to every hit from the Beatles, you will understand how good they were. And if you listen to their songs that would have been hits for anyone else, you will understand it even more.