What does it mean
Piece of cake
that was easy
let the cat out of the bag
share a secret by mistake
A little birdie told me
someone told you a secret
at the drop of a hat
to do something right away
hit the books
study very seriously
Break a leg
Good luck
Hold your horses
Wait a moment
slipped my mind
I forgot, I did not remember
apple of my eye
to cherish or prize something or someone above all else
things would look up
things would improve
sleep on it
i'm going to think about it
The elephant in the room
a big problem no one is talking about
cold feet
Scared to do something
On cloud nine
Very happy
make your move
take action
out of the blue
A fish out of water
Feel weird or out of place
Cost an arm and a leg
Very expensive
time is money
time is valuable, do not waster your time
turn over a new leaf
to change for the better
when pigs fly
it's never going to happen
Kill two birds with one stone
Do two things in one go
once in a blue moon
something that happens very rarely
beat around the bush
avoid a subject or question by talking about topics not related to subject or question
hit the nail on the head
to be exactly right