Out of the blue

Walt suddenly decided to invest in laser tag.

— Breaking Bad S3E11

Everything was going great until he suddenly reappeared out of the blue.

— Brooklyn Nine-Nine S5E11

And one day, out of the blue clear sky, I got a letter from Jenny

— Forrest Gump

I uh, I gotta tell you man, I mean, that's uh, it's kinda out of the blue, I mean don't you think?

— Friends S2E19

IT'S JUST LIKE THAT WOMAN, NO WARNINGS, NO DISCUSSION, THEN OUT OF THE BLUE, "I'M COMING NEXT WEEK."

— Gilmore Girls S1E18

She turns up out of the blue.

— Gossip Girl S3E15

And out of the blue, you'll be right there with her, so close she'll think she can touch you, and then all of this will just...

— Grey's Anatomy S5E7

I didn't want to just viciously attack someone out of the blue like some kind of...

— How I Met Your Mother S6E13