Take a pair of jeans or denim shorts that are too long, and mark them at the length you want the cut-off shorts to be. Do not mark them high enough up to cut off the ends of any pockets or the bottom of the crotch. You may mark straight across the legs or at an angle so that the middle is longer than the sides.
Fold the pants so that the side seam is facing up with one leg flat over the other. Use scissors to cut one leg starting from the outside seam toward the inner seam. Cut the other leg to match the first. Try on the shorts to make sure they are the desired length.
Use a seam ripper, box cutter or another knife to make holes in the shorts near the cut edges. Place the shorts flat on a cutting board when cutting them to avoid damaging the surface below. Use your fingers to separate the threads at the bottom and the edges of the holes to fray the edges. Run the shorts through the washing machine to distress them fully.