One widely circulated tidbit is that Lennon was inspired by James Joyce’s Finnegans Wake while writing the song. This would fit nicely with the Lewis Carroll homage, since Humpty Dumpty figures in Joyce’s stream-of-consciousness masterpiece as well. (Finnegan’s fall from a ladder resonates with the fall of Humpty Dumpty and the Fall of Man.) According to Beatles lore, “goo goo goo joob” are “the last words uttered by Humpty Dumpty before his fall.” This was a popular notion among the conspiracy theorists who were convinced that Paul McCartney had died in a mysterious accident and looked for clues to his demise in Beatles lyrics.
The only problem with the Joycean theory is that “goo goo goo joob” does not actually appear in Finnegans Wake. The closest approximation in Joyce is “googoo goosth,” which doesn’t quite have the same ring to it. There’s also no evidence that Lennon was actually reading Finnegans Wake at the time, so the imprint of Joyce is not nearly as clear-cut as that of Lewis Carroll.
From: Celebrating the Beatles: Goo Goo Goo Joob!
The other tidbit that folks use to tie I Am the Walrus to the Wake, not mentioned here, is that the book’s protagonist Humphrey Chimpden Earwicker / Haroun Childeric Eggeberth / HCE, is described as a walrus of a man, for both his girth and his mustache. And that’s about it. Again, nothing particularly convincing, so I’m glad to see a good debunking. More interesting in this article is the speculation about which came first: “goo goo g’joob” or Simon & Garfunkel’s “coo coo cachoo” (or is it ‘boop oop a doop’)?