Need help choosing a stretchy fabric for a costume?

A friend of mine doesn't have a costume for Halloween this year, and I thought I could try my hand at sewing (since I have a good enough idea of how it works) and make him a simple costume. He's simply looking for something ghostly like.. a not-too-loose black cloak with sleeves that droop and a hood. Any suggestions for a stretchy fabric that I can use? Something that's easy to pull over, please!