From WikiPedia -
“Rum and Coca-Cola” is the title of a popular calypso. Originally composed by Lord Invader and Lionel Belasco, it was copyrighted in the United States by entertainer Morey Amsterdam and became a huge hit in 1945 for the Andrews Sisters, spending ten weeks at the top of Billboard's U.S. Pop Singles chart.
Although the song was published in the United States with Amsterdam listed as the lyricist and Jeri Sullavan and Paul Baron as musical composers, the melody had been previously published as the work of Trinidadian calypso composer Lionel Belasco on a song titled “L'Année Passée,” which was in turn based on a folksong from Martinique. The original lyrics to “Rum and Coca-Cola” were written by Rupert Grant, another calypso musician from Trinidad who went by the stage name of Lord Invader. (The true credits for music and lyrics were restored in a plagiarism lawsuit won by attorney Louis Nizer, the account of which can be read in his book, My Life in Court.)