source of quote "That's the beauty of it. It doesn't DO anything."

[Sam Clements]

"What does it do?"
"That's the beauty of it. It doesn't <i>do</i> anything."

This question comes up on many a board.  It is one of those familiar things that we all KNOW we've heard in a movie(or somewhere).  But no one can come up with the source.  

It was posted in this thread http://boards.straightdope.com/sdmb/showthread.php?t=317339
over at the Straight Dope board.  I remember searching for it a year ago.   I was convinced it was from Willie Wonka and the Chocolate Factory.  It evidently isn't.

Any help here?  And apologies in advance if this is too trivial for the ADS-L.

Sam Clements