"She Said, She Said" (The Beatles)

Apart from being one of Ringo Starr's best performances on tape (his drum fills here are a thing of wonder), "She Said, She Said" is one of John Lennon's best compositions on the album Revolver (1966).
The Beatles were staying at a rented house in Beverly Hills during a break from touring in mid-1965, when Roger McGuinn and David Crosby of The Byrds dropped by with LSD, ready to party.  Everyone (with the exception of Paul McCartney) got their dosage and started tripping.  However, George Harrison began to panic, telling the others that he felt like he was dying.  Actor Peter Fonda, who also happened to be in attendance, tried to console Harrison by assuring him that he wasn't dying, repeatedly telling him, "You're not dying; I know what it's like to be dead," while simultaneously showing The Beatle a bullet wound from childhood, the result of a gun accident that had almost killed him.  
Whatever Fonda's intentions, the discussion of death and bullet wounds freaked Harrison out that much more.  Lennon, ever the big brother to Harrison, berated Fonda for talking about death, chiding him with, "You're making me feel like I've never been born!"
As McGuinn later recounted to Rolling Stone, "We were all on acid, and John couldn't take it.  John said, 'Get this guy out of here!'  It was morbid and bizarre."
To stick it to Fonda, Lennon wrote a song that he initially called "He Said, He Said," about the incident in LA, incorporating Fonda's words (I know what it's like to be dead) as well as his own retort (You're making me feel like I've never been born) into the song's lyrics.  Ultimately, Lennon decided that "he said" didn't sound quite right, so he changed it to "She Said, She Said."
It's a favorite of mine because it sounds deceptively simple: a straight-ahead rocker with a bit of West Coast influence.  But there are subtle things in Lennon's composition that are pure genius—like switching from 4/4 to 3/4 and back again on the bridges, utilizing the shifting time signature as a way to indicate dialogue between two people who aren't really syncing up intellectually.  Same thing with Lennon's chiming rhythm guitar against Harrison's almost brass-like lead.
It also has a pure, mid-60s guitar sound and a simple but effective bassline, which is played by Harrison, not McCartney.  (Like the party that inspired the song, McCartney sat this one out.)