This being their later works, it was part of The Beatles' LSD "phase", which was a topic in a variety of their songs.
the lyrics read
"Picture yourself in a boat on a river,
With tangerine trees and marmalade skies
Somebody calls you, you answer quite slowly,
A girl with kaleidoscope eyes."
the term is used among those who are both LSD or other hallucinagen users, and fans of The Beatles. It is a way of saying that some one is "Tripping" on LSD. The term is used because when hallucinating, you may see strange things, lots of colors, and a shifting world; All like looking through a Kaleidoscope.
"That gave me Kaleidoscope Eyes, man!"