It might well be called a Doberman in a jar; Black and Tan is the name given to an alcoholic drink comprising a 'mixture' of Ale and Stout, or sometimes Lager and Stout.

The name itself derives from a political reference to the black constabulary and khaki military uniforms of an irregular fighting force 'The Black and Tans' who were recruited in 1920 to counter Irish nationalists.

Normal practice for making a Black and Tan is first to pull half a pint of Ale into a pint pot, and then, using a spoon placed under the tap, to roll the Stout oh-so-gently on to the top of the Ale layer.

Done properly, the procedure produces a Black and Tan, black Stout on the top and tan Ale (or lager) underneath. Brownian Motion aside, the two beers won't mix in the glass until they are disturbed, for example, by drinking.

A classic Black and Tan consists of a foundation of Bass Pale Ale topped by thick black Guinness, the combination of English and Irish beers somehow cementing the origin of the name.