Back in the day, I bought an Army Mummy sleeping bag. It was rated to -10 below. A crazy friend of mine had one similar so we decided to put them to the test. A cold winter night was predicted just a little north of zero degrees so we slept out all night, on the ground with just a tarp between us and bare earth, behind my house. The dang things worked and we didn't get cold at all. The only problem was, I got a ittle frost bite on the end of my nose. Looked like a big pimple.
