Under the weather
Feeling slightly ill.
Piece of cake
Something very easy
Once in a blue moon
Very rarely
Raining cats and dogs
Raining very heavily
Spill the beans
Reveal a secret.
Fish out of water
Feeling uncomfortable or out of place.
Hit the nail on the head
To be exactly right about something.
Bite the bullet
To endure a difficult situation bravely.
Pull someone's leg
To joke with someone by teasing them.
Catch someone red-handed
To find someone doing something wrong.
Give someone the cold shoulder
to ignore someone
