butcher's apron

Origin: The apron worn in a traditional butcher's shop often has blue and white stripes and may acquire red bloodstains in the course of the work, thus bearing a passing resemblance to the red, white, and blue design of the Union Jack. Metaphorically, the pejorative allusion is to the bloodshed blamed on British imperialism. Origin information sourced from Wiktionary contributors (CC BY-SA 4.0).