Piece of Cake: It means that something is easy or simple.
Costs an arm and a
leg: An expression to say that something is
expensive or costly or difficult to achieve.
Break a leg: to wish good luck to another person.
Let the cat out of the
bag: It means tell a
secret.
Hit the nail on the head: When you have matched or say exactly
what the person wanted to say.
When pigs fly: Used to express disbelief.
You can’t judge a book by
its cover: don't judge people by their physical
appearance.
Bite off more than you
can chew: It refers to when we try to do too many things at the same time and
have just stressed.
Scratch someone’s back: To help another person.
See eye to eye: Say to explain whether or not someone is on the same
wavelength as us.