In Peter Weir's film "The Mosquito Coast," the foreign
missionary/preacher who travels with Harrison Ford's character and his
family to the Mosquito Coast says, what sounds like 'jaydoof' after he
says 'AMEN!' when he is preaching or speaking, to emphasize the
statement - JAYDOOF! AND AMEN! - and I am trying to figure out the
origin and meaning of the phrase/word, or what the word actually is
(if it is not spelled this way)... I searched in Gooogle with every
variation of the phonetic spelling I could think of... so any help
would be much appreciated... THANKS!

The missionary is the Reverend Spellgood.  In the book (Avon
paperback) he is recorded as saying '"Jee-doof! ... loave ... the
Load's marcy ..."' (p.85).  Apart from that (and on a quick flick
through), he seems to have no other vocal oddities.  As I say, just a
quick flick through the book, I could be very wrong.

Not a lot of help, but it gives you the spelling.  I'm afraid I don't
have the time right now to check more fully, but this could give you
(or some other Researcher) something more to go on.

Good luck!

I suspect its either Dutch, literally translates as "I am deaf" , but
colloquially means I am not worthy

or German literally translates as "I am silly/stupid/dumb" and also
means I am not worthy

but I'm not a linguist :)

Possibly needs a german/dutch speaker to confirm.

willie-ga

I believe Reverend Spellgood's exclamation is a variant of the Dutch
phrase "ben je doof?"-- literally meaning "Are you deaf?", but used in
a slang sense to mean "Are you an idiot?"

In "The Mosquito Coast," Reverend Spellgood, I think, is using "je
doof" as a fairly meaningless conversational padding, in the way that
some American teens place a "you know?" in every sentence, or
stereotypical Canadians with their "eh?"

The English slang word "doofus" is almost certainly related to the
Dutch and German "doof."

Google Web Search: "ben je doof"
://www.google.com/search?lr=&cr=&q=%22ben+je+doof%22&hl=en&ie=UTF-8&oe=UTF-8&newwindow=1&safe=off

Hi! 

Sorry for the delay in reply -- and THANK YOU so much for the
comments!!! This was really a mystery, and all the information you
both shared sounds correct to me -- I really REALLY appreciate the
help... Google Answers is truly amazing... ;)

Big Thanks, Jee-Doof, Amen! --- Xusah ***