Piece of cake
Something is easy to do
Cost an arm and a leg
Something is very expensive
Once in a blue moon
Something happens rarely or not often
Hit the nail on the head
You have done something exactly right
Break a leg
A wish for good luck
Bite the hand that feeds you
To deliberately hurt or offend a benefactor
Kill two birds with one stone
To accomplish two tasks with a single action
Spill the beans
To accidentally reveal information that was supposed to be a secret
A blessing in disguise
Something that seems bad or unlucky at first, but results in something good happening later
Beat around the bush
Not saying directly
Under the weather
Feeling ill / Getting a cold
To burst someone’s bubble
To do or say something that proves someone else’s beliefs are not true
Walk on eggshells
To be very careful with your actions and words
Bite the bullet
Finish something no matter how unsatisfying or unpleasant it is / Get something over with
Beating a dead horse
Overdoing something or an action that is pointless
Let the cat out of the bag
Reveal a secret carelessly
Elephant in the room
A controversial problem or a major issue
Like two peas in a pod
Be together always
Like riding a bicycle
A skill that you learn and will never forget
On thin ice
Used to refer to a sensitive scenario or a person who is in trouble
When it rains, it pours
When everything goes wrong at once
Wear your heart on your sleeve
To be extremely open about what you feel and think
Grass is greener on the other side
Never being satisfied with what one gets
Cry over spilt milk
Worrying or complaining about something that cannot be fixed/rectified
Bark up the wrong tree
Following a misguided or mistaken thought or action