Everyday
As easy as ABC
Something is very easy
Cross your fingers
For good luck
A little birdie told me
Someone told me a secret
Hit the hay
Go to bed/sleep
Get your act together
Behave properly
Have a change of heart
Changed your mind
Cry crocodile tears
To pretend to be upset
When pigs fly
To say something is impossible
Draw a blank
Can't remember / Don't know
Get cold feet
Be nervous
Hold your horses
Wait a minute / Not so fast
Horsing around
Fooling around
Have second thoughts
Have doubts
See eye to eye
Agree
Fish out of water
Being somewhere you don't belong
Play it by ear
Improvise
Speak your mind
Say what you really feel