A “sit-upon” is described by the 1940 Girl Scout Handbook as follows: “A sit-upon is a piece of waterproof material about eighteen inches square that a wise hiker carries along in a compact roll to use while resting, eating, or sitting around the campfire.”
I decided to knit myself one after a long, cold day of rock climbing last January, when I spent many hours sitting on freezing rocks. My sit-upon is knit in a ribbed cable with a rugged worsted wool, which yields a dense, reversible, and doubly-thick fabric. An oilcloth backing makes it waterproof.
It’s perfect for keeping you warm and dry when you have to sit on rough rocks, damp ground, or stadium seats.