sitdown strike: huelga de brazos cruzados (o brazos caidos)

according to wikipedia, "A sit-down strike is a form of civil disobedience in which an organized group of workers, usually employed at a factory or other centralized location, take possession of the workplace by "sitting down" at their stations, effectively preventing their employers from replacing them with strikebreakers or, in some cases, moving production to other locations."

(thanks to Jorge Lawton for the cruzados version, not sure exactly how it varies by country but both should be understandable)