My mother told me once that if you hitch up your pant legs several inches just before sitting down, it will prevent the knees from stretching out. Plus it will take tension off the legs so they will last longer and the pants don't winkle as much either. Ever since she told me this tip, I have made a habit to pull them up. Now it is just second nature. I notice that it is also more comfortable when sitting and my pants are never winkled or stretched out.. Does everyone else do this when sitting?