Diabhal r-phost nua!
I recently changed my Gmail account over to Irish, and my empty inbox declares "Diabhal r-phost nua!" I hadn't encountered the word "diabhal" yet, so I looked it up -- it means "devil." So, this is saying, "(A) Devil new email," which has got to be idiomatic. Where does that come from? How did we get "The Devil, aka Beelzebub, the Prince Of Darkness," to mean "None?"
Probably the same way "The hell you will!" came to mean "Oh, no you won't!"
We've even got the same expression in Croatian, halfway across the continent - it doesn't really invoke the devil, it's just a way of refusing or negating something. I wonder how many other European languages have the same thing.