A piece of cake
A task or activity that is easy to complete
Eat like a horse / pig out
Eat a lot
break a leg
good luck
Kill two birds with one stone
To solve two problems with one action
Feeling under the weather
sick
cost an arm and a leg
very expensive
Two peas in a pod
very similar
White lie
ex: We told Grandma that her cake was delicious, which was actually a white lie.
an innocent lie to protect another person's feelings
Fishy
ex: I knew something fishy was going on when I saw all of my friends' cars in my mom's driveway.
odd, suspicious
On cloud nine
ex: He's got a new car for his birthday. He's on cloud nine.
very happy
all ears
fully listening
Bring home the bacon
ex: He worked hard every day so he could bring home the bacon and live a good life.
earn money
catch red handed
ex: The kids were caught red handed stealing chocolate bars.
catch someone in the act of doing something wrong or illegal
cat's got one's tongue
said about someone who doesn't speak (usually due to shyness) / silent / quiet
Every cloud has a silver lining
ex: I'm not going on holiday this year, but every cloud has a silver lining, as I'm able to spend more time with my family at home.
every difficult or unpleasant situation has some advantage
cold feet
nervous
Have a bigger fish to fry
Have more important things to do
born with a silver spoon in one's mouth
ex: Rafathar is a lucky boy. He was born with a silver spoon in his mouth.
born into a rich family
Head in the clouds
ex: Mike thinks he is going to pass his exams without studying. He has his head in the clouds!
Have unrealistic / impractical ideas / daydreaming
pull one's leg
ex: I was just pulling your leg. I'm not really a police officer.
joke or tease someone