Hey, he didn't make up a nonsense phrase, that's the way we were taught this story! Still, as a kid, I noticed it didn't exactly rhyme, even when you say "Englishmun." But it's not really poetry, it's a giant ogre who's both angry and hungry. The next lines do rhyme: "Be he alive or be he dead, I'll grind his bones to make my bread." This comic is from Chris Hallbeck at Maximumble. There's a bonus punchline here.