Fie, foh, fum, I smell the blood of an Englishman
The phrase has no allusory meaning and, apart from when quoting Shakespeare or Jack the Giant Killer, there's little reason ever to use it.
It is best known from the nursery rhyme - Jack the Giant Killer:
I smell the blood of an Englishman.
Be he alive or be he dead
I'll grind his bones to make my bread.
The source is anonymous and the date is unknown. It must have been before 1596. It is referred to by the English dramatist Thomas Nashe, in Have with you to Saffron-walden, 1596:
"O, tis a precious apothegmatical Pedant, who will find matter enough to dilate a whole day of the first invention of Fy, fa, fum, I smell the blood of an English-man".
How true. Let's not spend the whole day on this and finish with Shakespeare's alternate version, from King Lear, 1605:
"Child Roland to the dark tower came,
His word was still, Fie, foh, and fum,
I smell the blood of a British man."
See other phrases and sayings from Shakespeare.