In Cold Blood

If you do something, especially kill someone, in cold blood, you do it in a way which is cruel because you plan it and do it without emotion. 

Four men were charged with the killing, in cold blood, of a French tourist last summer.
An unarmed boy was shot in cold blood outside his home yesterday.

In the Hot Seat

Definition:

in a position where you are responsible for important or difficult things 

Examples:

He suddenly found himself in the hot seat, facing a hundred angry residents at a protest meeting.

She has been the woman in the hot seat at this company during the last five difficult years.

COLD FISH

Examples:

1. He isn't very demonstrative, but his mother was a cold fish so he probably gets it from her.
 

Definition:

A cold fish is an unfriendly or distant person who is difficult to become friends with and has no emotions. This expression was used by Shakespeare in The Winter's Tale but became popular in 1900s.

black Idioms 

as black as a skillet

- very black

My hands were as black as a skillet when I finished working on the car engine.

as black as a stack of black cats

- very black

The little boy was as black as a stack of black cats after playing outside all day.

as black as a sweep

- very dirty/black (a chimney sweep cleans chimneys and becomes very black)

My friend was as black as a sweep after he finished cleaning the basement.

as black as coal

- very black

My friend's cat is as black as coal.

as black as night

- very dark and black

The old house was as black as night when we entered it.

as black as pitch

- very black

My face was as black as pitch after cleaning the stove all morning.

as black as the ace of spades

- very black

The horse in the parade was as black as the ace of spades.

black and blue

- bruised

My shoulder was black and blue after I fell down the stairs.

black and white

- either good or bad, either one way or the other way but not in between

Our boss sees everything in black and white although he knows this is impossible.

black box

- an electronic device such as a flight recorder that can be removed from an aircraft as a single package

The investigators searched for a long time in order to find the black box of the airplane.

black eye

- a bruise near one's eye which makes it appear black

The man received a black eye when he bumped into the closed door.

black market

- the place where goods/money are illegally bought and sold

We sold some cigarettes on the black market during our travels.

black out

- to darken a room or building by turning off the lights

During the war people in the cities were forced to black out their windows so nobody could see them.

black out

- to lose consciousness

The man blacked out during the parade and he had to sit down and rest.

black sheep (of a family)

- a person who is a disgrace to a family or group

The man is the black sheep in his family and has not made a success of his life.

blackball (someone)

- to exclude/ostracize someone socially, to reject someone

The businessman was blackballed in the industry because of his bad business practices.

blacklist (someone)

- to exclude/ostracize someone, to write someone's name on a list if they break some rules

The sports federation blacklisted the swimmer because he was using steroids.

blackmail (someone)

- to extort/take money from someone by threatening him or her

The photographer tried to blackmail the famous actress with some photographs that he had taken.

blackout

- a temporary situation where you do not release some information

The government decided to have a blackout regarding the information related to the political prisoner.

black-tie event/affair

- a formal event where guests wear semi-formal clothes with men wearing black bow ties with tuxedos or dinner jackets

The award ceremony for the movie awards was a black-tie affair.

in black and white

- in writing, officially

I put down my complaint in black and white.

in (someone's) black books

- to be in disgrace or out of favor with someone

The boy is in his girlfriend's black books because he was late for their date.

in the black

- to be successful or profitable

Our company has been in the black since they began to cut costs