(transitive, simile) To have an extensive and penetrating understanding of (something or someone).

To be spoiled; to have an easy life without appreciating it.

(idiomatic, vulgar) Synonym of I don't know

(idiomatic, vulgar) To be well-informed concerning a particular subject; to have a capable command of a particular area of expertise.

It is necessary to be informed in order to do the right thing in a given situation.

(dated) Synonym of know what is what

(dated) Synonym of know what is what

(vulgar, idiomatic) I have no idea whatsoever

(idiomatic) retort to questioning about a person by a stranger, when one does not want to confirm or deny knowing or being the person.

To understand one's rank or status and behave accordingly; to act humbly.