Out of the blue

*** Out of the blue



"Why did she do that?" Answer: "I have no idea. It was completely out of the blue."

In this expression the word 'blue" has anything with the color or the feeling but the surprise. We don't know what the girl did but we are sure that nobody expected that. It was suddenly. Without a signal or something like that.

In my country, Brazil, we use another expression : "do nada, sem mais nem menos"