Icing on the cake
When you already have it good and get something on top of what you already have

Keep an eye on him
You should carefully watch him

Cup of Joe
A cup of coffee

Every cloud has a silver lining
Be optimistic, even difficult times will lead you to better days

Cock and bull story
An unbelievable tale

Curiosity killed the cat
Being inquisitive can lead you into a dangerous situation

A penny saved is a penny earned
By not spending money, you are saving money (little by little)

A leopard can't change his spots
You can't change who you are

A bird in the hand is worth two in the bush
Having something that is certain is much better then taking a risk for more

Charley horse
A cramp or stiffness in muscle

Light as a Feather
It Means, Light in weight;delicate and airy.

Joshing Me
It Means, Tricking me.

High on a Hog  
It Means, Living on luxury.

Over the Top
It Means, Very excessive.

Bakers Dozen
It Means, Thirteen.

Dry Run
It Means, Rehearsal.

Dead Ringer
It Means, 100% Identical, Duplicate.

Without A Doubt
It Means, For Certain.

Under The Weather
It Means,Feeling ill or sick.

A Blessing In Disguise
It Means, Something good that isn't recognized at first.

A Piece Of Cake
It Means, A task that can be accomplished very easily.

Blue Moon
It Means,A rare event or occurance.

Cry Wolf
It Means, Intentionally raise a false alarm.

Chow Down
It Means, To eat.

Drink Like A Fish
It Means, To drink very heavily.

A  Dime A Dozen
It Means,Anything that is common and easy to get.

A Slap On The Wrist
It Means,A very mild punishment.

Hold Your Horses
It Means, Be patient.

Hit The Sack
It Means,Go to bed or sleep.

Hit The Nail On The Head
It Means, Do something exactly right or say something exactly right.

Hit The Books
It Means, To Study, especially for a test or exam.

Head Over Heels
It Means, Very excited and/or joyful, especially when in love.

He/She Lost His/Her Head
It Means, Angry and overcome by emotions.