This phrase reminds me of the Calvin and Hobbes cartoon where the first 3 panels are of the two of them sitting immobile on the side of the bed, staring at Mom with rapt attention as she lectures. In the last panel, Mom has just said, "Do you understand?", and Calvin talks out of the side of mouth to Hobbes: "Sounds like she must be finally winding down--start nodding".
And wow, you sure can learn something every day. I went to Max's page for some shortcuts to phrase origin sites, and guess what, I got sidetracked. Was intrigued by the title 'not-so-famous last words'. He(?) has citations for many of the words, but not for this one:
ZYZZYXDONTA a snail with characters the extreme opposite of Aaadonta. I wonder if he put that in just to see if people were paying attention; I can't imagine that that's true. Here's the home page; last words are P. 18:
http://members.aol.com/gulfhigh2/words.html 
