What is a word or phrase in everyday use conversation and informal writing but inappropriate for formal situations?

There are many words and phrases that are perfectly acceptable in everyday conversation and informal writing, but would be considered inappropriate in formal situations. Here are a few examples:

Slang:

* "Chill" (meaning "relax" or "calm down")

* "Hang out" (meaning "spend time together")

* "Cops" (instead of "police officers")

* "Awesome" (instead of "excellent" or "remarkable")

* "Dude" or "Bro" (as a general term of address)

Informal language:

* "Gonna" (instead of "going to")

* "Wanna" (instead of "want to")

* "Gotta" (instead of "have to")

* "Y'all" (instead of "you all")

Idioms and colloquialisms:

* "Kick the bucket" (instead of "die")

* "Bite the bullet" (instead of "face a difficult situation")

* "Spill the beans" (instead of "reveal a secret")

Vulgarity or profanity:

* Any curse words or offensive language.

The level of formality appropriate for a given situation depends on several factors, including the audience, the topic, and the purpose of the communication.

For example, you might use informal language with friends or family, but you would likely use more formal language in a business meeting, a job interview, or a formal essay.

It's always a good idea to err on the side of caution and use formal language in situations where you are unsure.