Body
Cross your fingers
Easy as ABC
Something that is very simple or easy
Very easy
Night owl
Someone who stays up late
Let the cat out of the bag
Tell a secret
Get cold feet
To feel nervous
Draw a blank
To forget something
Cool as a cucumber
Very calm in a stressful situation
The teacher's favorite student
Raining cats and dogs
Raining heavily
I'm all ears
You have my full attention
Get a kick out of it
To feel entertained by something or someone
Goose is cooked
Now you're in trouble
When pig's fly
To say something is impossible
Fish out of water
Being somewhere you don't belong
Change your mind/feelings on something
It's in the bag
It's a certainty
A bad egg
Someone who is often in trouble
You can't teach an old dog new tricks
The older you are the harder it is to learn new things.
Hold your horses
Wait a minute
See eye to eye
Two people agree on something
In the same boat
To be in the same situation as someone else
Spill the beans
Tell the truth/a secret
Curiosity killed the cat
Asking too many questions may get you in trouble
Snail's pace
To move very slowly