you can't judge a book by its cover

Barnaby Rudge

[Cockney slang]judge

beggars can't be choosers

Something is better than nothing: those who can't provide for themselves should accept whatever help is available.

blot one's copy book

To damage one's own reputation through bad behavior.

blow someone's cover

To reveal that someone's behavior, situation, or identity has been fabricated or deliberately misrepresented for an ulterior motive.

book burning

Any mass destruction, removal, or recalling of books, motion pictures, broadcasts, or electronic works as a form of censorship, especially motivated by religious or political objections to the material.

book dumping

The practice of donating old used books that burden rather than assist communities.

book in

To check in (to a hotel).

break cover

To disclose one's real thoughts and intentions.