I first came across the word Cocqcigrues in Water Babies by Charles Kingsley. It apparently derives from French legend of fantastic animals unlike any ever seen. The expression, " A la venue des Cocqcigrues." means roughly "at the coming of the Cocqcigrues" (kok-se-groos)...which is to say "never". I read somewhere that Rabelais invented the expression (Gargantua and Pantagruel, chapter XLIX: à la venue des cocquecigrues).