To be/feel down in the dumps
To be or feel sad or depressed.
To be tickled pink
To be very happy.
Till the cows come home
For a very long time.
To pull someone's leg
To be just joking.
Rise and shine
Wake up and be happy!
Close, but no cigar
You were close, but you didn't make it.
To get a slap on the wrist
Give someone a mild punishment.
To be Greek to somebody
To be impossible to understand.
To keep someone's chin up
To be happy.
To hold someone's horses
To be patient and wait.
To cost an arm and a leg
To be very expensive.
Hands down
Without competition.
To be or feel under the weather
To not feel well.
To be as sick as a dog
To be very sick.
To be in the same boat
To be in the same position or unpleasant situation as other people.
To be a loose cannon
To be unpredictable.