4B (or "Four No's") is a radical feminist movement originating in South Korea in 2019. Its members renounce four activities: sex, child-rearing, dating, and marriage with men. Jung Se-young and Baeck Ha-na, two proponents, criticize marriage as reinforcing gender roles in South Korea. The movement draws some amount of inspiration from the novel Kim Ji-young, Born 1982, as does South Korea's Me Too and "Escape the Corset" movements. The 4B movement claimed to have 4,000 members in 2019.