A large mouthed plastic bottle (think Gatorade) used by a trucker in lieu of other facilities. True road kings can use one while holding 65. Some truckers dispose of trucker's toilets by tossing them out the window, and if you keep an eye out, you'll spot these half-full gems along interstates everywhere.
With a wind chill of -40 on Wyoming's I-80, Todd decided to forgo the Rest Area. The trucker's toilet in the heated cab of his Kenworth came in real handy.