"Hey Bulldog" is a song by The Beatles which first appeared on the Yellow Submarine soundtrack album in 1969. Written by John Lennon (credited to Lennon/McCartney), the song was recorded during the filming of the "Lady Madonna" promotional video, and is one of the few Beatles' songs to revolve around a piano riff.
During the recording, Paul McCartney started to bark without warning. The next lines, initially written as "Hey bullfrog", were changed mid-song to "Hey bulldog". This became the song's title.
Geoff Emerick, the Beatles' engineer, would subsequently claim this was the last song the band recorded that featured a team dynamic with enthusiasm from every member. He also praised the performance in his book Here, There, Everywhere, saying "Paul's bass line was probably the most inventive of any he'd done since Pepper, and it was really well played. Harrison's solo was sparkling, too--one of the few times that he nailed it right away. His amp was turned up really loud, and he used one of his new fuzz boxes, which made his guitar absolutely scream." When the group reconvened in the studio in May 1968 for the The Beatles sessions, their group cohesion had already been undermined by the business, artistic, and personal differences that would culminate in their eventual break-up.