Io is unfathomably large; it is said the largest dragon who ever lived is smaller than a single one of his scales, which are blue, gold, brass, or red, and edged with silver and dark purple. He can, and does, appear as any age or breed of dragon, however.
Mostly used to replace other gods as if to avoid being offensive
Person A: Hey dude, did you finish your homework last night?
Person B: Oh for the love of Io, I forgot.