Out of the blue: Something happens unexpectedly and suddenly. Blue here meaning sky. "I was walking along the street and from out of the blue this car came speeding by and almost killed me" In black and white: In writing. In the old days of typewriters paper was white and ink was black so to get something in black and white meant you wanted it in writing. In the red: Losing money. Accountants used black ink for profits and red ink for debits. If you were in the red you were losing money. Red tape. Bureaucratic stuff. Hoops you have to jump through (another good English idiom) to get things done. "Getting a visa to come to the USA is so hard because of all the red tape." Green light. Approval, a go ahead, an okay to proceed. Traffic signals have red and green. What happens when it's green? "After I finish all the red tape for my visa I'll get the green light to go to the USA".