Having just read Richard Lederer's comments on the -gry riddle, I have finally found the answer. It's similar to the game we used to play in junior school, where someone would say to you, "Constantinople is a very long word; if you can't spell it you're a dunce." A non-dunce would spell it, whereas a dunce would start spelling Constantinople before being laughed out of the playground.
Lederman, however, thinks this is "Nonsense. Humbug. Hogwash. Tripe. Flapdoodle. Folderol. Balderdash. Baloney." I think he's missed the point.