grinfuck verb1 •(slang, vulgar) To behave in a superficially polite or charming way while simultaneously acting in a deceptive, manipulative, or harmful manner.Ms Fiorina stared at and even shouted at the mysoginists. She was tired of being "grinfucked", she yelled at one man she believed was trying to do her down. — 2006 formsgrinfucked · grinfucking · grinfucks