The term "shammy" comes from the word "chamois," which refers to the hide of an animal such as a deer or sheep. This is a very soft and super-absorbent material, so it's perfect for using after you've washed your car or when you have a wet surface to dry. It's a little bit tricky at first, but once you know the proper steps, you'll be drying your car off in no time.
Place the chamois on the hood of the car and spray it down using the hose. Most chamoises dry to a hard shape after use, so you want to completely saturate the chamois to loosen it up to a malleable state. Wring it out and soak it twice.
Wring out the chamois and lay it flat on the surface you want to dry. Hold the two corners closest to you with your index finger and thumb, then pull the chamois toward you, keeping it as flat as possible against the surface of the paint. This will remove all of the major water spots from the surface.
Turn around and wring out the chamois so you don't get water on your newly dried surface. Ball up the chamois with your hands, then run it against the area you just dried to ensure that the small water spots are gone.
Repeat steps 2 and 3 until the car is completely dry. Once it is, store the chamois in a dry location so that it doesn't develop mould or mildew.