The first time I heard it was from the editorial director, Mike McCarthy. Eventually, "Mac" faxed me a letter from his Uncle Hugh, who said, "Why don't publish something like DOS for Dummies?" The request was for a computer book for people who don't want to fall in love with computers. That was Mac's take on the whole thing.
About two years after the book was published, IDG Books began to circulate PR about how IDG President John Kilcullen thought of the name. The story varies:
* At first, Kilcullen overheard the name mentioned while eating dinner with some computer publishing poobah's in New York City.
*Later renditions have Kilcullen hearing the title at a software store or, sometimes, a book store. He overhears a customer ask for "a book like DOS for Dummies." Kilcullen then files this request away in his bain for some reason. (Obviously because any reporter worth his salt would then ask John, "Well, why didn't you write the book yourself if you thought it was such a hot idea!?")
* I've also heard of a press release that states Kilcullen's brother came up with the name.
Whatever.
Recently, Kilcullen has titled himself "creator" of the For Dummies series. This doesn't jibe with my sense of history. Primarily, the contract I signed was not for a series of books. (Even today, computer book publishers develop a book series in a wholly different manner than DOS for Dummies was developed.) So this whole "creator of the series" story is malarky. No, if anything, he successfully exploited the success of one book into a series.
Update: May 2001. In the latest bit of B.S. PR from Kilcullen, he now claims to have "peddled" the idea for the Dummies series to several publishers before being hired at IDG Books specifically to launch the series. This is the worst of the lies yet. Trust me on this one, it was myself who was peddling the idea for a line of beginner books.