Expressions that are accepted in informal writing and used by the general public, but not used in formal writing are called a. idioms. b. colloquialisms. c. jargons. d. euphemisms. e. clichés.

I believe the answer is B.colloquialisms.

You can see this in words that spoken between friends or family.

For example:
Y'all must be Crazy !!

Here are the full paper, you can go nuts on it.

I wanna new  car