dirty word

air one's dirty laundry in public

To reveal one's sordid secrets to the public.

air one's dirty linen in public

Synonym of air one's dirty laundry in public.

bad word

A vulgar word.

breathe a word

To divulge even part of a secret (usually used with a negative).

Dicky

[Cockney slang]word

via dickie bird

dirty laundry

Unflattering or embarrassing facts, or questionable activities that one wants to remain secret, but which someone else may use as blackmail.

dirty look

An unpleasant or disdainful look or expression, often directed at someone.

dirty money

Money that is illegally gained, illegally transferred or illegally utilized, especially money gained through forgery, bribery, prostitution, money laundering, or theft.