Animals
Raining cats and dogs
It's raining very hard
Cross your fingers
For good luck
Piece of cake
Very easy
Have a green thumb
Good at growing plants
A pain in the neck
Someone or something that annoys you
Night owl
Someone who stays up late
Slipped my mind
I forgot
One smart cookie
Out of the blue
Call it a day
Time to quit
Pig out
To eat a lot
Have a change of heart
Changed your mind
Spill the beans
Reveal the truth
True colors
Someone's real self
Give it a shot
To try to do something
Snail's pace
To move extremely slow
Speak your mind.
Say what you really feel
Cool as a cucumber
Very relaxed
To see red
To be very angry
Hold your horses
Wait a minute
Teacher's pet
The teacher's favorite student
Agree
Nuts about something
Like it a lot
Have the blues
To be sad or depressed
Break a leg
Saying good luck to someone