10 English Idioms. Part 1 1. "To feel blue" - if you say, I am feeling blue, it means, you are feeling sad. 2. "Out of the blue" - if you say, it happened out of the blue, it means, it was unexpected, it happened suddenly. 3. "Red flag" - if you say, something is a red flag, it usually means, that there is a problem or a danger, that you should deal with. 4. "To catch someone red-handed" - you can use this expression, when you have found someone doing something that he wasn't supposed to do. 5. "The grass is always greener on the other side" - you can use this expression, when you talk, for example, about person, which always is unhappy with his situation, and which looks at other people and thinks, that their life is better. 6. "The grass is greener where you water it" - this idiom tell us, if you want achieve some points, you should work hard, harder than usuall. Than your grass will be more greener (It means, you'll be succesfull person) 7. "Make hay while the sun shines" - do something, while you are able to do it. Not later, because you can't know, what will be tomorrow. Today, while you are full of energy and health. 8. "When in rome act like the romans" - this phrase means, that you should follow the rules of area, in which you are living or visiting. 9. "Hit the Nail on the head" - don't be shy! Say something, what is right or true 10. "Speak of the devil" - you can use this Idiom, when an object of discussion becomes during the conversation out of the blue.