You will need:
an old sweatshirt
bed pillow, poly-fill or other stuffing
one lucky dog
1. stuff sleeves and shoulder/collar area of sweatshirt (you might need to put in a few stitches to create a "pocket" in the body of the shirt.)
2. insert pillow through bottom of shirt.
3. stitch end of sleeves together
4. attach pillow "ring" to bed bottom with a few stitches