"Happy Jack" is a song by the British rock band The Who. It was released as a single in December 1966 in the UK, peaking at No. 3 in the charts. It was also their first top forty hit in the United States, where it was released in March 1967 and peaked at #24. It was included on the American version of their second album, Happy Jack, originally titled A Quick One in the UK.
The song features Roger Daltrey on lead vocals with John Entwistle singing the first verse, making it one of the only songs composed by Pete Townshend to feature Entwistle on lead vocals. At the tail end of "Happy Jack", Townshend can be heard shouting "I saw you!", and it is said that he was noticing drummer Keith Moon trying to join in surreptitiously to add his voice to the recording, something the rest of the band disliked.
According to some sources, Townshend reported the song is about a man who slept on the beach near where Townshend vacationed as a child. Children on the beach would laugh at the man and once buried him in the sand. However, the man never seemed to mind and only smiled in response.
The song was first performed by The Who in 1967 and continued to be played until 1970; a performance from The Who's legendary February 1970 concert at Leeds may be heard in a medley with other songs on the 1995 CD reissue of Live at Leeds and subsequent reissues. It was also performed in Townshend's first solo concert in 1974. The most recent performances of the song were short (one-and-a-half-minute) versions at the Shepherd's Bush Empire, London, on December 22 and 23, 1999.
A snippet of the song was played at a 1982 concert in Indianapolis to appease a fan who was holding a sign saying, "Play Happy Jack, It's My Birthday!", which was blocking the vision of several fans behind him. However, Townshend stated that he and the band couldn't remember how to play the full song anymore.