Getting stuck in the mud or snow is never fun, but you can make the problem worse by damaging your transmission or some other expensive component. Gently rocking in an attempt to free the car is fine. But if it looks as though you're really stuck, stop. Repeatedly throwing your car from forward to reverse, as well as spinning tires at high speeds creates heat that is hard on transmissions, clutches, and differentials. If you are really stuck call a tow truck, it may be cheaper in the long run. It's always a good idea to carry a small fold-up shovel and a traction aid in your trunk, like sand, gravel, or cat litter.