A list of colourful English idioms...
feeling blue = feeling unhappy: "What's the matter with you? Feeling blue?"
out of the blue = completely unexpected: "I sent off my application to the company, but heard nothing. Then completely out of the blue they sent me a letter."
see red = become extremely angry: "When people are cruel to animals, it really makes me see red."
a red letter day = a day of great importance: "It's a red letter day tomorrow in the company. It's our fiftieth birthday!"
paint the town red = celebrate: "They went out last night and really painted the town red - they didn't come home until 5 a.m."
in the red = overdrawn: "It's the end of the month and we're in the red again. We have to control our spending better."
like a red rag to a bull = likely to make someone angry: "Don't talk to him about politics - it's like a red rag to a bull."
red tape = bureaucratic paperwork: "You have to cut through a lot of red tape to get proposals accepted in this company."
red carpet treatment = treat someone with great respect: "When we visit our offices in Asia, we get the red carpet treatment."
get the green light = get approval to start something: "We've finally got the green light to start research on the new product."
green fingers = be a good gardener: "Everything grows in her garden. She definitely has green fingers."
green-belt area = an area of protected land surrounding a town or city: "The green-belt area around London is disappearing fast."
green politics = environmental politics: "He's in green politics and often campaigns to fight pollution."
black market = illegal trade: "You can change dollars for a much higher rate on the black market."
black economy = a part of the economy unregulated by the authorities: "He doesn't pay any taxes and thinks that the black economy will make him rich." (He's working on the black.)
give someone a black look = look at someone as if you are angry: "Why is he giving me such a black look?"
on the black list = be on a list of "undesirables": "We won't be invited to their party this year - we're on their black list."
blacklisted = be banned: "Many actors and writers were blacklisted in Hollywood in the 1950's because they were considered "un-American."
in black and white = be extremely clear: "This contract is in black and white: we aren't allowed to keep any pets in this house."
black spot = a dangerous spot: "his roundabout is a black spot for traffic accidents."
black and blue = be badly bruised: "When she fell off her bicycle, she was black and blue for days."
white Christmas = when it snows at Christmas: "There hasn't been a white Christmas here since 1983."
whitewash = cover up the truth: "I don't believe his story. I think it's all a whitewash."
a grey area = something which is not definite: "I think genetic engineering is a bit of a grey area."
grey matter = your brain: "Doing crossword puzzles tests your grey matter."