What is "fee-fi-fo-fum"

interj. (alt form fee-faw-fum English)

"Fee-fi-fo-fum" is the first line of a historical quatrain (or sometimes couplet) famous for its use in the classic English fairy tale Jack and the Beanstalk. The poem, as given in Joseph Jacobs's 1890 rendition, is as follows:

Fee-fi-fo-fum, I smell the blood of an Englishman, Be he alive, or be he dead I'll grind his bones to make my bread.

Though the rhyme is tetrametric, it follows no consistent metrical foot; however, the respective verses correspond roughly to monosyllabic tetrameter, dactylic tetrameter, trochaic tetrameter, and iambic tetrameter. The poem has historically made use of assonant half rhyme.