An injunction to workers to 'down tools' come out on strike.
During the 1970s in the UK this phrase was synonymous with militant union activity. It was used when workers were called out on strike, although more often in drama and literature than in reality. The work that made the phrase known was the 1960s BBC sit-com 'The Rag Trade', where it became a catchphrase. The show was set in a clothing factory and virtually every episode included the shop-steward Paddy (Miriam Karlin) blowing a whistle and shouting "Everybody out!".