You know what I mean,
This song is a perfect illustration of the unique way in which John Lennon and Paul McCartney collaborated as writers. One would often begin a song with a basic idea or snatch of lyrics, and the other would help mould it into a complete piece. McCartney, who came up with the initial idea, commented:
"I had 'She was just seventeen' and then 'never been a beauty queen'. When I showed it to John, he screamed with laughter, and said 'You're joking about that line, aren't you?'… It was one of the first times he ever went 'What? Must change that...'"
John suggested the line be changed to 'You know what I mean', which Paul thought was 'really cool' - and so it stuck.