Use some clear packing tape to create a ghost effect. You can wrap the tape sticky side out around your arms / body as a form. Or use a cheap form from a craft store. The coat the sticker side with a layer facing the other direction.
Uplighting is key to make it look cool.
NOTE: Weather is not a tape ghost’s friend. Condensation will start to form between the tape layers. Don’t expect to reuse a tape ghost the next year.