money machine

Money obtained in a devious or sneaky manner.

(slang, originally, US) A fast car.

Mean machine is slang for a powerful, impressive, or formidable vehicle — especially a fast car that commands respect the moment it rolls by. Originally American, the phrase has spread widely and can also describe any piece of equipment or even a person who operates with ruthless efficiency. Whether it's a muscle car growling at a red light or a professional athlete at the top of their game, calling something a mean machine is a high compliment wrapped in cool, understated swagger.

Any machine operated by placing money or a token into a slot, especially.