You only need a square piece of black cloth. Panne velvet would be good. Diagonale should be as long as the distance between your hands.
Then cut a hole in the middle for your head. Attach two cords in the opposing corners (That you can tie around your wrists). Cut arches in the side of the cloth, to make it batwing-shaped. Wear a black hat with pointy ears or a black mask or black facepaint....
General idea about how it could look:
if out get little paint and fake blood you can paint a lot if you have a good hand
A kangaroo. Tape a paper bag to your belly and BOOM, you're a kangaroo.
Mummy-Cover yourself in toilet paper
Oooh, i like that :)