What you need:
To make body:
Spray each garment a little at a time with glue (make sure to work on a drop cloth and in a ventilated area). Press and wrap the streamers all the way around until shirt and pants are completely covered. (To prevent glue from seeping through, stuff sweatshirt and sweatpants with plastic grocery bags). Tear streamers every so often, and leave some stragglers. For a worn and tattered effect, color the edges of streamers with brown marker.
To make headpiece:
From white card stock, cut out an oval large enough to allow your child's face to be framed, making sure his view will not be impaired in any way. Open the white bag, and glue card-stock oval to the inside. With a utility knife and using card stock as a guide, cut out oval face shape from paper bag. Trim 60 slits up from the bottom of the bag's opening at the sides, front, and back. Fit bag over child's head and adjust. Remove bag, and stuff with plastic grocery bags. Use the spray glue to add streamers in the same manner as before. (When dressing your child, have him put on the mask first. This way, the bag ends can be neatly tucked into the sweatshirt.)