Ben Zimmer in Word Routes:
Today is a big day for Beatles fans: the band's entire catalog is being reissued in digitally remastered form, and the video game “The Beatles: Rock Band” is also set for release. And what better day than 09/09/09, considering the band's love of the number nine (enneaphilia?), from “The One After 909” to “Revolution No. 9.” In honor of the latest wave of Beatles nostalgia, I've been mulling over a bit of nonsense from the fertile mind of John Lennon: the timeless chant heard in “I Am the Walrus,” “Goo goo goo joob.”
Originally released as the B-side of “Hello Goodbye” and as a track on the Magical Mystery Tour album in November 1967, “I Am the Walrus” has been an endless source of lyrical debate. And that's just how Lennon wanted it: he reputedly constructed the song to be as confusing as possible, in order to keep the Beatle-ologists busy. The chorus of the song goes, “I am the eggman, They are the eggmen, I am the walrus, Goo goo goo joob.” The “walrus,” Lennon later confirmed, was an allusion to the Lewis Carroll verse, “The Walrus and the Carpenter,” from the children's classic Through the Looking-Glass. It's believed that the “eggman” is a nod to the character of Humpty Dumpty in the same book. But what of “goo goo goo joob” (also transcribed as “goo goo ga joob” or “goo goo g'joob”)?
One widely circulated tidbit is that Lennon was inspired by James Joyce's Finnegans Wake while writing the song.
More here.