Idioms explained

"To get cold feet"

To be frightened suddenly about doing something which you had felt fine about before.
"Olivia always gets cold feet before she goes on stage."

"To let someone off the hook"

To refrain from punishing someone even though they deserve the punishment.
"Johnny was caught stealing apples last week. The farmer let him off the hook this time but said next time he'll call the police."

"To be snowed under"

To have too much work on hand.
"The insurance companies are snowed under with claims after all those floods last month"

"To bite the bullet"

To suffer something with courage. (Before anaesthetics wounded soldiers on the battlefield would be given a lead bullet to hold between their teeth while the surgeon amputated.)
"I hate the hoover and it's awful noise but my cleaning lady is sick and the house is filthy. I'm going to have to bite the bullet and vacuum the place myself."

"To flog a dead horse"

To insist on some focus, issue or topic that is no-one is interested in any more. (Flog is a synonym of "whip")
"Please stop trying to get the company to provide a special place to smoke. Nobody's listening and your just flooging a dead horse."

"To call it a day"

To decide to stop work until the next day, usually because one is tired and feels it's enough.
"That's 300 trees we've planted and it's getting dark. Time to call it a day I think."

"To cost an arm and a leg"

To be very expensive.
"I'd love to buy a sports car but they cost an arm and a leg."

"To cut corners"

To take short cuts: to find ways of reducing the work involved in a job - often implying that the result will be inferior.
"You can't cut corners when you're planning anything as complex as a space programme. The slightest error could be catastrophic."

"To let the cat out of the bag'

To give away a secret, to accidentally divulge private information.
"Gentlemen, you are the only ones to know of this possible take-over-bid. I must emphasise that it will succeed only if nobody here lets the cat out of the bag."

"To think outside the box"

To have, or look for, a completely new idea, especially if unrelated to previous experience.
"'Nudge' ideas, are often the result of thinking outside the box. In the Paris Metro (subway) they used to make announcements before the arrival of every train to get people to stand away from the edge of the platform. Now they just have a band of plastic on the edge of the platform with bumps on it. They are uncomfortable to stand on. It works much better - and it's quieter."