California YIMBY, an organization founded eight years ago to promote housing construction in response to an ever-increasing gap between demand and supply, held a victory party in San Francisco recently. Welcome to the most victorious of California YIMBY's victory parties, Brian Hanlon, founder and CEO of the organization, told attendees. Its acronym (Yes In My Backyard) symbolizes its years-long battle with NIMBYs (Not in My Backyard), people and groups who have long thwarted housing projects by pressuring local governments that control land use.