Idioms involving animals
Raining cats and dogs
Raining really hard
Have your cake and eat it too.
You want it all.
Fit as a fiddle.
In great health.
Green with envy.
Very jealous.
The cat's got his tongue. (Has the cat got your tongue?)
He's having trouble talking/is being silent. (Why are you being quiet?)
Sour grapes
Someone is grumpy over something
He has a serpent's tongue.
Once in a blue moon.
Not very often.
Hair of the dog (that bit you).
Something that you ate/drank that made you sick - you should have some more to make you feel better.
Piece of cake
Over the moon.
Very happy.
White as a sheet.
Someone is very pale due to fear, anger, being sick.
Let the cat out of the bag.
Told a secret that shouldn't have been told.
He wants a piece of the pie.
He wants some of the profits.
Frost is on the pumpkin
It's beginning to get cold (fall/autumn)
A horse of a different color (a horse of a different hue)
That's a very different thing.
Quiet as a mouse.
Very, very quiet.
Bit off more than he could chew.
Little pitchers have big ears.
Be careful, the kids are listening.
He is yellow.
He's a coward.