A piece of cake
To cost an arm and a leg
To see eye to eye
The cat is out of the bag
Cat got your tongue ?
Once in a blue moon
Burn the midnight oil
It´s raining cats and dogs
Speaking of the devil
something is very expensive
the person you´re just talking about arrives
to work until late at night
something is very easy
very rarely
It´s raining heavily
agreeing with someone
someone is quiet and isn´t talking
to accidentally reveal a secret
