Let the cat out of the bag
Reveal a secret
A wolf in sheep's clothing
Someone who is dangerous but pretends to be harmless
Hold your horses
Be patient; wait
Copycat
A person who does the same thing as someone else
Birds of a feather flock together
People who are alike tend to stay together
Cost an arm and a leg
Very expensive
Don't count your chickens before they hatch
Don't count on something that hasn't happened yet
Cool as a cucumber
Very calm; Relaxed
Has the cat got your tongue
Quiet; not able to speak or give a response
Make a mountain out of a molehill
To make something that is unimportant seem important
Elvis has left the building
Something has come to an end; it's over
Drive me up the wall
To irritate or annoy
Have an axe to grind
To be in dispute with someone
Go the extra mile
Going above and beyond what is required
Head over heels
Very excited; Joyful; Deeply in love
Hit the hay
Go to sleep
Lend me your ear
To politely ask for someone to listen
On the fence
Have not decided or make a decision; Undecided
Pig out
Eat a lot or eat fast
Raining cats and dogs
Very loud, heavy rainstorms; Pouring
Something smells fishy
Noticing that something isn't right; Something is suspicious
Until the cows come home
A long time
Break a leg
To wish someone good luck
Once in a blue moon
A rare event or occurrence
When pigs fly
There is no way that is going to happen; impossible