Animal Idioms
Food Idioms
Body Part Idioms
Clothing Idioms
100

Raining cats and dogs

Raining really hard

100

piece of cake

easy, simple

100

Break a leg

good luck!

100

blow your socks off

to surprise

200

Hold your horses

To wait or slow down

200
cheesy

silly 

200

all ears

listening closely

200

caught with your pants down 

unprepared

300

Let the cat out of the bag

Accidentally reveal a secret

300

Not your cup of tea

Not something you enjoy

300

cold feet

nervous, having second thoughts

300

bursting at the seams

not fitting anymore

400

Butterflies in your stomach

Nervous or anxious

400

spill the beans

to tell a secret

400

zip your lips

keep a secret 

400

at the drop of a hat

ready to go without further notice

500

kill two birds with one stone 

Get two tasks finished at one time

500
Don't cry over spilled milk
Don't get upset over something that has already happened and you cannot change
500

On the tip of my tongue

when you know something but cannot remember 
500

to wear your heart on your sleeve

not afraid to show your emotions