When you're hanging Christmas lights, you don't have to use nails! You can use hooks or clips that can attach to the gutter, the eaves of your roof, or even to the inside of a window frame. These are easy to use, and you won't have to worry about damaging your walls or roof. If you don't have any hooks or clips, you can also use Command strips or other removable adhesive products to attach the lights. Just remember to be gentle when removing them so they don't leave any residue behind.