For the caveman costume, buy fake fur in a brown or gray tone, about double
the length of the person's torso.
Fold it over and cut away the neck along the fold, plus one shoulder to underneath the armpit. Sew up the sides, making sure to leave armholes.
Buy a nylon dog bone and attach it to the top of the remaining shoulder.
I made a necklace from leather thong and strung animal "teeth" on it. Make the teeth from clay or playdoh, allowing ample time to dry. Pierce them with a skewer so they dry with a hole in them, then string them on the leather thong.
Give yourself a crazy messed up hairdo with gel, dirty your face with smudges. Make sure you grunt a lot! This was a prize winner! Our party was indoors so we went barefoot, but shoes don't really matter.
Thanks to Wendy for this fun idea!