The White House obtained its name because it was repainted white after the British burned it in 1814.
American blue laws were so named because they were originally printed on blue paper.
Companies used to dismiss employees by distributing notices printed on pink slips of paper.
Red light district comes from the practice of railway brakemen leaving their lanterns on cathouse porches.
Blackmail is so designated because letters of extortion were sent by mail.
Many common terms and phrases derive from color-related words. And just as our perceptions are sometimes "colored," so are our explanations for some of our more colorful phrases.