Black and Tan
n. pl. Black and Tans 1. A two-toned drink consisting of a layer of ale topped by a layer of stout.
2. A member of a paramilitary force recruited in Britain and sent to Ireland as part of the Royal Irish Constabulary to suppress the Sinn Fein rebellion of 1919 to 1921.
[Sense 2, from the colors of the original uniforms of the force, which combined khaki army trousers with dark-colored police jackets and caps due to lack of supply.]