A piece of cake- The test was a piece of cake.
A task or activity that is easy to complete
Get the green light- We got the green light to start the project
To get permission to do something
Bookworm- She is a bookworm who reads every day.
Someone who reads a lot
Raining cats and dogs- It's raining cats and dogs outside
Raining very heavily
Look like a million bucks- You look like a million bucks today.
To look and feel fantastic
A couch potato- He is a couch potato on the weekends.
A lazy person who watches too much television
Once in a blue moon- I eat fast food once in a blue moon.
Very rarely
As quiet as a mouse- The class was as quiet as a mouse.
Very quiet
Lightning fast- The runner is lightning fast.
Extremely fast
Bring home the bacon- She works hard to bring home the bacon.
To earn money, to achieve success
That is the way the cookie crumbles- We lost the game, but that's just the way the cookie crumbles.
That is just how it is
To pass with flying colours- She passed her exam with flying colors.
To pass something with a high score
Eat like a horse- After practice, I eat like a horse.
Eat a lot, in large quantities
Feeling under the weather- I stayed home because I was feeling under the weather.
To feel mildly ill or sick
Money does not grow on trees- Don't waste money, it doesn't grow on trees.
It is not easy to get money, implies that the person you are addressing spends money too easily
Have bigger fish to fry- I can't worry about that, I have bigger fish to fry.
Have more important things to do
The grass is greener on the other side- He thought the new school would be better, but the grass isn't always greener on the other side.
People think that they will be happier if things were different
Kill two birds with one stone- I walked to school and exercised, I killed two birds with one stone.
To solve two problems with one action
On cloud nine- She was on cloud nine after winning.
Very happy
Rome wasn't built in a day- Keep practicing, Rome wasn't built in a day.
It takes a long time to do something worth doing
Two peas in a pod- They are like two peas in a pod.
Nearly identical, very similar
A golden opportunity. This job is a golden opportunity.
A very good chance to achieve something
Let the cat out of the bag- He let the cat out of the bag with the surprise party.
A secret that was supposed to be kept quiet that was told
Head in the clouds- He has his head in the clouds during class.
to daydream
Put your money where your mouth is- If you believe in it, put your money where your mouth is
To do something rather than just to talk about it