It's raining cats and dogs
It's raining heavy.
That was the last straw. (I'm not going to do this anymore.)
That was the last (bad) thing to happen and I'm not going to put up with it/her/him/them anymore.
Burst into tears
Suddenly start to cry.
Bare your soul.
Tell someone your secret thoughts and feelings.
Break a leg
Good Luck!
Don't spill the beans.
Don't tell anyone the secret.
When pigs fly.
something that is never going to happen.
We don't see eye to eye.
We don't agree.
Lose your head
lose control of your emotions.
Lose your temper.
Become very angry.
See red
Get really angry.
Get a grip on yourself.
Get control of your emotions.
That was a piece of cake.
That was easy.
He was on pins and needles waiting for his grades.
He is anxious and worried about his grades.
I feel under the weather.
I don't feel well.
I have butterflies in my stomach.
I'm nervous.
"Keep a straight face".
Try not to smile or laugh.
Sleep like a log.
Sleep really soundly and deeply.
That costs an arm and a leg.
That costs a lot of money. It's expensive.
I'm going to hit the sack.
I'm going to bed to sleep.