idioms

  golden rule (a very important rule to follow in a particular activity) The golden rule of a happy marriage is to learn some give and take. The golden rule is to use the best ingredients when cooking.   envocabulary.com

  easy money (money made without much effort) We started drug dealing as a way of making easy money. Many young people today look for easy money. My friend made easy money by selling insurance.

    when pigs fly  US informal (that will never happen; impossible) They will win the game. – Yeah, when pigs fly! When pigs fly, she’ll clean up the kitchen. He will repair the doorknob only when pigs fly.   envocabulary.com

  break a leg  spoken (good luck) I’m sure your performance will be the best. Break a leg! Break a leg, Molly. You’ll be great. We use the expression “break a leg” to wish someone luck, especially just before they perform on stage.   envocabulary.com

  once in a blue moon (hardly ever, very seldom) My elder son is abroad. I see him once in a blue moon. Once in a blue moon, I get the chance to go to the movies.   envocabulary.com