The idiom "black hole" is used to describe a state of complete darkness or emptiness, often metaphorically. It can also refer to a person who is difficult to communicate with or understand due to their lack of responsiveness or unfriendliness.

The idiom "wash dirty linen in public" refers to exposing a problem or issue that is best left private or hidden. It suggests that airing dirty laundry, or bringing up unpleasant topics or details, can harm one's reputation or image.

The idiom "if you scratch my back, I'll scratch yours" is an expression used to convey that if someone does something nice for you or helps you out in some way, you will do the same for them.

"Shoot the breeze" is an idiomatic expression that means to pass time or chat casually, often about trivial matters. It can also mean to gossip or talk about someone behind their back.

The idiom "cry over spilt milk" means to regret or lament over something that cannot be changed, usually after a mistake has been made. It can also mean to waste time or effort on something that is fruitless or pointless.