"Fum Fum Fum" (pronounced "foom") is a 16th or 17th century Christmas carol that originated in the Catalonian region of northeastern Spain. The word Fum means smoke in the Catalan language but could also refer to the sound of a drum, a fiddle, a strummed guitar, or a rocking cradle.

The rhythms of the song probably stem from the Sardana, a courtly Catalonian dance. In this exciting version for string orchestra, the theme appears in its entirety from letters A to B, followed by a set of four variations. The first variation shows off the cellos and basses, while the second variation provides a highly ornamented version of the tune for the first violins. The third variation is a slow waltz featuring the second violins and violas, and the work concludes with a jubilant G major march, slightly reminiscent of the "Finale" of Beethoven's 9th Symphony.