ACTION
ANIMAL
BODY
FOOD
OTHERS
100

easier said than done

be more easily talked about than put into practice

100

when pigs fly

something will (most likely) never happen

100

break a leg

good luck

100

piece of cake

something is very easy

100

be on the same age

think, know or behave in the same way as someone

200

sink or swim

a situation in which you will fail if you do not make a lot of effort

200

kill two birds with one stone

to achieve two things at once

200

two-faced

not to be trusted

200

in a nutshell

very briefly, in a short way, giving only the main points

200

be on cloud nine

extremely happy and excited

300

hit the hay

to go to sleep
300

snake in the grass

an unpleasant person who cannot be trusted

300

keep a straight face

to try to stop yourself from smiling or laughing

300

spill the beans

to tell the secret information

300

not in a million years

something is extremely unlikely or impossible

400

kick the tires

to try something or examine it carefully before you buy it

400

Cat got your tongue?

this is said to someone who would not speak

400

all ears

someone who listens carefully

400

the apple doesn't fall far from the tree.

a child usually has a similar character or similar qualities to his or her parents

400

on thin ice

when somebody does something risky

500

face the music

to accept responsibility for something you have done 

500

smell a rat

to believe something is wrong

500

in the blink of an eye

when something happens at a very short time

500

turning over a new leaf

to start over, to act in a different manner or change your attitude about something

500

be on the same boat

to be in the same unpleasant situation as other people