The song was largely written during a recording session at EMI Studios on 18 September 1968 by John Lennon and Paul McCartney. McCartney: "We thought, 'Why not make something up?' So we got a riff going and arranged it around this riff. So that is 50–50 John and me, made up on the spot and recorded all in the same evening." During the session, the Beatles and the recording crew made a short trip around the corner to McCartney's house to watch the 1956 rock & roll movie "The Girl Can't Help It" which was being shown for the first time on British television. After the movie they returned to record "Birthday".