Colors
Foods
Body Parts
Animals
Geography
100

to feel sad

to feel blue

100

something that does not work, usually an electrical appliance or mechanical item

a lemon

100

someone who talks too much and cannot keep secrets

a big mouth

100

the first person to arrive somewhere, a person who gets out of bed early

an early bird

100

very inexpensive

dirt cheap

200

jealous of someone else's good fortune

green with envy

200

nonsense

baloney

200

by memory, memorized completely

by heart

200

not able to see well because of very bad eyesight

as blind as a bat
200

to make a big problem out of a small problem

to make a mountain out of a molehill

300

something (written or spoken) that is not true but that causes no harm

a white lie

300

in trouble, in a tricky situation

in a pickle

300

to like sweet foods and candy very much

to have a sweet tooth

300

afraid, scared, cowardly

chicken

300

Almost never, very rarely

once in a blue moon

400

complicated official procedures and forms

red tape

400

something that is very easy to do

a piece of cake

(easy as pie -- ok, too)

400

madly in love

head over heels in love

400

not taking advice, stubborn

pigheaded

400

a small part of a larger problem

the tip of the iceberg
500

by surprise, unexpectedly

out of the blue

500

suspicious, not right or honest

fishy

500

to joke, kid, or trick someone

to pull someone's leg

500

to talk openly and directly

to talk turkey
500

in trouble

up the (or a) creek