Can anyone here explain SCHWA?

I was wondering if there were any fans of Bill Barkers SCHWA books, And if they have a grain of truth to the "subliminal messages" or if its just a humorous take on the whole UFO subject.
The whole SCHWA thing apparently went right over my head, and I only recently found an interest, ordered a couple books online an seems interesting...

Oh, I loved SCHWA!
I had the stickers all over my gear back when I played in a punk band.
It never struck me as anything other than humourous, though.

just skimming throught the pages though it seemed almost as if there was some sort of cryptic message, just me I guess.