Get giant vent tubes. You can probably get some at any home improvement store like Home Depot or Lowe's. Paint it pink or whatever color you want your worm to be. Let your head hang out of the top. You might want to think about it though...you won't be able to use your arms & it might be hard to walk. If you want to use your arms, just attach some sort of suspenders (i.e. - string) so it can hang off your shoulders.
Make a long tube of fabric. Take a long rectangle of fabric that will fit around up, and sew it the long way.
Before you do that, you may want to emphasize the "segments." You can sew ribbons across, or just draw them with fabric paint.
You could go to an appliance store and get a large washer/dryer or refrigerator box; split it open long ways and put it in the bathtub or somewhere to soak it and roll it into a round tube big enough to go around your body. lay it down flat rolled up and let it dry. To secure it around your body, you can use wide strips of red or brown fabric to look like the segments of the worm. This is what holds it closed around you (so make sure you were something underneath) Before wetting, you should measure where your arms would be and cut them out after it is dry (or it will stretch the holes). For the head, get a pair of large dark brown pantyhose and put them over your head. You can make a small slit where your mouth and nose are if it's hard to breathe through.
You could even go even further and make a hook out of foil and attach to the top of the pantyhose on your head. [ Annerszz_101's advice column | Ask Annerszz_101 A Question ]
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