to accidentally reveal a secret

Let the cat out of the bag

To go out and enjoy something flamboyantly

Paint the town red

To reveal true character or intentions

Show your true colors

To reveal a secret

spill the beans

To do something immediately, without any hesitation

At the drop of a hat

someone who is gifted by the ability to talk

Gift of the gab

The phrase is used to describe when someone agrees with another person or views something in the same way.

See eye to eye

To describe exactly what's causing a situation or problem

Hit the nail on the head

To suspect that something is wrong or that someone is being dishonest.

Smell a rat

To end the conflict and make peace.

Bury the hatchet

used to point out something that's get done at the very last moment or almost too late.

At the eleventh hour

To brag about one's own achievements

Blow one's own trumpet

feel sick or unwell

under the weather

used to express for something thats costly or expensive

Cost an arm and a leg

To get into trouble or difficult situation

Get into hot water

To keep talking about something that's already been resolved or is no longer relevant or to waste effort on something that is unlikely to succeed

Flog/Beat a dead horse

To avoid the topic and speak in a roundabout manner.You can use it when someone is avoiding talking about an important topic and trying to talk around it.

Beat Around the Bush

To do everything possible to achieve something

Leave No stone unturned

This idiom was coined to describe a rare or infrequent event.

Once in a Blue Moon

The term is used to describe something that happens suddenly and unexpectedly

a bolt from the blue

To stop working for the day or to stop doing something

call it a day

To remove the tension at a first meeting, at the opening of a party, etc.

Break the ice

To have a grievance against someone or a personal reason for complaining or being involved in something

Have an axe to grind

facing the consequences of your deeds

Face the Music

a pointless or hopeless pursuit.

Wild goose chase

These are some most repeated idioms and phrases.. you can you these to improve your communication skills 

Smell a rat

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The prevalent theory of dishonesty