out of the blue; bolt from the blue; complete surprise
Idiomatic expression for something sudden and unexpected, often used when someone says or does something abruptly without context.
Out of the blue, he said, "Let's get married."
I was surprised by the sudden, unexpected question.
Standard kanji spelling for this idiomatic expression.
Mixed kana-kanji spelling; the first part is often written in kana.
Literally 'a stick from a thicket', evoking the image of a stick suddenly poking out of a bush. The exact origin is uncertain, but it vividly conveys something abrupt and unexpected.