|Assorted Beatles and Beach Boys hanging out with the Maharishi, circa 1967-68.|
Unfortunately, there are no examples of the Beatles singing, say, "God Only Knows" (though we can pray that there might be moldering acetate of such a blessed event out there somewhere); "Back In the USSR" is, however, obviously an oblique Beach Boys reference. And as you can see from the picture above, they had a shared interest in transcendental meditation. Some fans even say that it's implicit from the lyrics ("Full speed ahead, Mr. Barkley! ... Aye, sir, fire!") that the yellow submarine was really on the hunt for the Sloop John B—probably one reason why the crew of the latter had such an awful time on board.
Additionally, let me take you down: check out my now fully-linked-up archive of things I've written here. Nothing to get hung about.