This is a simple costume with an awesome effect. The total cost of the costume to me was free because I already had everything I needed.
But, in case you want to try this, here is a materials list:
The clothes that you are wearing
Extra pants, shoes and hoodie
A mannequin head (I got one of the Styrofoam display heads from a Halloween shop)
The tools that I used were a drill and drill bits.
Step 1: Step 1: Positioning the Mennequin Head
For this step I used an ordinary backpack and stuffed it with a pillow. I took advantage of the way the zippers came together at the top and place the mannequin head right in the pocket that it creates. I then took some shoelace and tied the zippers together so that they would not come apart. This held the mannequin head very nicely.
Step 2: Step 2: Hoodie and Jacket
The fact that it is so cold out by the end of October in New England works to my advantage when layers are required to cover up certain aspects of the costume that need to be covered up. In this picture, all I am wearing is the backpack/mannequin head combo, a hoodie to cover that, and a jacket. As you can see, it already has a creepy effect.
The tan jacket is put on first and then the backpack. I pulled out the jacket sides and wrapped them around the backpack straps, effectively hiding them.
The brown hoodie is put on the mannequin head first, then I brought the zipper of the hoodie around my waist and zipped about one or two inches of zipper right in front of my belt. Finish the effect off by wrapping the hoodie arms around your stomach/chest and knot them to stay.
Step 3: Step 3: Make Some Legs
This costume is cheap AND good for the environment. For the legs, I duct taped together empty beer cans for the structure and then wrapped some blanket around those with more duct tape.
I used an old pair of shoes that I sometimes wear and just drilled small holes in the sides just big enough to fit a shoelace through. I then wound the shoelace through more holes drilled into the fabric.
Fun tip: Drilling fabric is hard. The fabric usually just starts wrapping around the drill head. I found that reversing the drill direction and drilling that way will still cut into the fabric but won't bind up.
I then inserted the legs into the pants and drilled more holes through the top of the fabric of the legs and the waistband of the jeans. More shoelace was used through those holes.
I stuffed a sheet down the back of the pants to fluff that part out a little and to simulate the buttocks and thighs. Although you can't really see those parts once everything is on, the extra cushion in the back will make the legs extend out further and make use of the knee joints to add to further realism (and also to keep the legs out of walking's way).
I used a nice thick belt to attach the legs to my body. I started the belt through the first two left loops of the jeans (like you normally would) and then wrapped the belt around my body, through the left backpack strap and around the backpack, then back through the right backpack strap, through the front right two loops of the jeans, then buckled it. This not only held very well, but flattened out part of the backpack that would have looks a little funny once the brown hoodie was on. Feeding the belt through the backpack straps prevented the belt from slipping down.
Step 4: Step 4: Wear It
The "put it on" part might actually be harder to do than the "making it" part. Here is the step-by-step way I put it on:
1: Tan jacket on
2: Backpack/mannequin head on
3: Pull jacket sides out and around backpack straps
4: Position the pants in front about chest-high
5: Wrap belt around body to secure pants (through front pants loops and backpack straps)
6: Brown hoodie on, cover the mannequin head with hood, zipper up an inch or two in front of waist, wrap arms around your torso and tie them off.
Here's a couple videos of this costume in action. I was able to do some interesting looking things wearing this, and about 10% of the people I ran into walked away thinking it was two people. Thanks for watching, and please VOTE if you like!