“Flak” refers to negative responses to a media statement or program. It may take the form of letters, telegrams, phone calls, petitions, lawsuits, speeches and bills before Congress, and other modes of complaint, threat, and punitive action. If certain kinds of fact, position, or program are thought likely to elicit flak, this prospect can be a deterrent.

— In our words · Source: Manufacturing Consent (Noam Chomsky & Edward S. Herman)