The title is pronounced "Jamaica," and is a play on the word: "She went to the Caribbean." "Jamaica?" "No, she went on her own." It could also be a sexual reference.
This song was meant to imitate Reggae and its "dub" derivative emerging from Jamaica in the early '70s. Bonham's inability to replicate a Reggae beat on his drums, however, turned the song into an odd melange of what sounded like '50s doo-wop and reggae. This song and "The Crunge" are considered the two "joke" songs on the album.
The distinctive drum sound was created by placing 3 microphones a good distance away from John Bonham's drums.
Led Zeppelin never performed this live. It would have been difficult to recreate the Reggae band.
This is one of the few Zeppelin songs where all 4 members share the composer credit.