A Freakonomics Quiz on Redonkulous New Words

New words are constantly being created in the English language. The word “ginormous” made it into the Merriam-Webster dictionary a few years back, in part because it could be traced back to a 1948 dictionary of British military slang.
A word I have been hearing the last year or two is “redonkulous,” (or alternatively “redonkulus”), which the Urban Dictionary defines as “significantly more absurd than ridiculous, to an almost impossible degree.”
What is the origin of the word redonkulous?
Searching on the web, I found discussions that all seem to center around recent mentions on sitcoms or movies.? And it certainly has the feel of a very modern word.
I was surprised, therefore, to stumble onto a version of the word redonkulous in print, spelled slightly differently, nearly 30 years ago.
So as a reward to those blog readers who are both hip and literate, we are offering Freakonomics schwag to the first blog reader who can identify the book where I saw this redonkulus reference.
Addendum: The answer is here.