Onhell said:One of his many acid trips?
A reasonable guess, as there were Beatles songs about that (see "She Said She Said" in particular).
But no, that's not right.
However - since this question has been up for a long time with no answer, perhaps it's time for a new question.
Here's the answer:
Lennon was referring to his acting role in the 1967 movie "How I Won The War".
Time for someone to post the next question.
And anyone who even mentions the king of Hawaii is going to get slapped with a freakin' pancake.