balls to the wall

back to the wall

A very difficult situation with no beneficial options available for action.

balls of steel

Courage, audacity.

bang one's head against a brick wall

To waste effort on a futile project.

blue wall of silence

Strict secretiveness maintained by the members of a police force with respect to information which might be contrary to their interests, especially information concerning questionable police actions.

break the fourth wall

To apparently communicate with reality directly, such as when characters of literature comment on the existence of a reader.

bust one's balls

To work very hard; to put in a lot of effort.

Chinese Wall

An information barrier within an organization, designed to ensure internal confidentiality; frequently used to prevent conflicts of interest.

Cobblers

[Cockney slang]balls or 'bollocks'

via cobblers' awls