Cats
Let the cat out of the bag
Give away a secret
When the cats away the mice will play
Walking on thin ice
Out of the blue
Something totally unexpected
Takes one to know one
You are just like me/just as bad as me
Cat's pajamas
The best thing, best dressed, best idea
beautiful or highly admired
Cold as ice
Very unfriendly
Once in a blue moon
Rarely happens
Child is just like their parent
Cat got your tongue?
Stay silent when expected to speak
Game of cat and mouse
Changing behavior to trap someone
Break the ice
Make a start
In the red
in debt, owing money
Hit the nail on the head
Get something exactly right
Curiousity killed the cat
Like herding cats
Tip of the iceberg
Can only see a small part of something much bigger that is typically problematic
Black sheep
It ain't over until the fat lady sings
It isn't over yet
Look like something the cat dragged in
A person that looks dirty, untidy, worn out
Cat burglar
A thief who is very quiet and agile in their ability to break into buildings
Put it on ice
Put a project on hold
Green with envy
Noticeably envious of something
Ignorance is bliss
You are better off not knowing