As a woman, New Yorker Norah Vincent was used to being stared at by men she passed in her Village neighborhood. It's a way men "assert their dominance," she says. But she often wondered what was behind those stares. So she conducted an experiment. Like John Howard Griffin, who disguised himself as an African-American in the South of 1959 for "Black Like Me," and Gregory Peck playing a writer posing as a Jew to investigate anti-Semitism in the Oscar-winning "Gentleman's Agreement," Vincent went undercover. With makeup, workouts, wardrobe and a voice coach, she became a man and plunged into a...