Where did the title Tomorrow Never Knows come from?

Tomorrow Never Knows took The Beatles into previously unexplored musical territory. Its use of tape loops, a mellotron, Tibetan chants and various Musique Concrete techniques were startling innovations for a mainstream pop record.

The title, however, was inspired by a more homely source, one shared by A Hard Day's Night:

I took one of Ringo's malapropisms as the title, to sort of take the edge off the heavy philosophical lyrics.

Even when dabbling in those 'heavy philosophical' lyrics John Lennon still had space for a Team Beatle joke.  

Did John Lennon understand the words of Tomorrow Never Knows?

The Beatles Story (teaching resources)