Out of the blue

After I hadn’t heard from her in six months, she called me out of the blue to meet for lunch.

I really can't understand how something like this could simply pop up out of the blue.

I deckhanded on a fish boat for four years and knew no fisherman likes to be called out of the blue and have his numbers demanded!

Just as it appeared Arsenal had taken the sting out of the tie, Johnson produced a moment of outrageous quality, thundering a bullet of a left foot shot out of the blue and into the top left-hand corner of Wojciech Szczesny's net with the Pole grasping at thin air.