Reach into the pocket, grasp the bottom and pull it out of the pants. The gum stain should be exposed.
Place the pair of pants into the freezer for several hours, or overnight for better results. The gum should be hard to the touch when you remove the pants.
Chip away as much of the gum as possible using the blade of a butter knife.
Saturate several cotton balls with a solvent, such as lighter fluid, acetone or isopropyl alcohol, and press them to the remaining gum stain. Allow the solvent to penetrate the gum and loosen it for several minutes.
Flake off the remaining gum stain using the butter knife.
Push the pocket back into the pants and launder as normal, or according to the care instructions printed on the tag.