An odd way in which slang takes on new meanings. "Jam Buttie" sometimes refers to a Police Patrol Car, on account of its usual colouring in Britain, which is white with a vivid red (sometimes reflective) stripe along both sides. The term is applied even to cars which have different colours to the reflective panels (such as a checkerboard yellow and blue pattern, used in Cheshire).

The term "Black Maria" is still applied to a prison van, even when its colouring is no longer black.