what are the plastic sheets called that soldiers sleep unter when sleeping outdoors?
I think you're talking about the poncho. They are not specifically designed for sleeping under, they are supposed to be a wet-weather overgarment. But, since they are basically just a big waterproof rectangle, they are about the most useful multi-purpose piece of equipment the Army issues.
In the Marine Corps we would drape our ponchos over our shelter halves for extra wet weather protection. So I suppose it does kinda look like a plastic sheet.
Two man Pup tents. Each person carries one shelter half. And they are rubberized plastic for flexability and endurance. Each shelter half has a hooded head hole and can be used as a pancho.
