Script (guión): Idioms, ‘out of the blue’. If something happens out of the blue then it happens unexpectedly and suddenly. I was crossing the road yesterday morning and out of the blue came a motorbike speeding towards me. Luckily, once again out of the blue, a bolt of lightening came down from the sky, struck the motorbike rider on the head and moved him out of my way so I was not hurt.