Bookworm
Someone who reads a lot
As quiet as a mouse
Very quiet
Eat like a horse
Eat a lot, in large quantities
Kill two birds with one stone
To solve two problems with one action
Let the cat out of the bag
A secret that was supposed to be kept quiet that was told
(a) little bird told me
I heard something (usually secretive or unknown) from someone (not named)
monkey see, monkey do
silly/unintelligent people tend to copy each other's actions
get the lion's share
get the greatest percentage
in the dog house
in trouble with another person
eager beaver
a person who is excited about doing certain work
Fishy
odd, suspicious
hold your horses
wait and be patient
holy cow!
Wow, I'm surprised!
horse around
play roughly
chicken out
to decide not to do something out of fear (usually just before)
clam up
become quiet and nervous suddenly
copy cat
a person who does the same thing as someone else
dog days
very hot days
dropping like flies
dying/giving up quickly
ants in one's pants
unable to sit still or remain calm out of nervousness or excitement
cat nap
a short sleep
Smell a rat.
Begin to suspect trickery.
Take the bull by the horns
Face a challenge or danger boldly
Raining cats and dogs.
Raining heavily
Until the cows come home
For a very long time