guerrilla proofreading
pp. Marking up a public sign to correct or point out a grammatical error or typo.
guerrilla proofreader n.

Example Citations:
On Wednesday, October 13, at the Decatur Library, writers Jeff Deck and Benjamin Herson will sign their new memoir The Great Typo Hunt: Two Friends Changing the World, One Correction at a Time. It's an English-action-packed memoir of public guerrilla proofreading that ultimately brought the authors in conflict against a misspeller with power: the U.S. federal government.
—Blue Elephant Book Shop, “Jeff Deck & Benjamin Herson sign 'The Great Typo Hunt' — Wed 10/13,” Facebook, October 7, 2010

Guerrilla proofreading does seem to be a popular hobby for some people. They can get quite agitated about apostroflies, invisible hyphens, and other such entities.
—Stan Carey, “Grammar to go” (comment), Sentence First, March 26, 2010

Earliest Citation:
LIST OF THE DAY: Some unusual findings sent in by you guerrilla proofreaders and grammar irregulars out there:
—Steve Harvey, “Only in L.A.,” Los Angeles Times, April 20, 1996

Related Words: