Michigan double
 n.— «Usually the double-trailer combinations, called “Michigan Doubles” in trucker parlance, carry steel or some other raw materials, while many of the single-trailer ones I’ve seen are fuel tankers (“Michigan Super Tankers”) that can haul as much as 17,000 gallons of gasoline, diesel, or kerosene.» —“Re: Truck-specific items on Michigan highways” by Larry Harvilla Usenet: misc.transport.road May 31, 2004. (source: Double-Tongued Dictionary)