Use a white sheet for cover and then cut eye holes and a mouth hole. Wear a white pair of sweat pants white socks and a white shirt and white tennis shoes. (you must wear white so it wont make you look green or something) Now you are ready to go Trick Or Treatin'.
Thanks to an anonymous submitter for this idea!
To be a ghost you need two things, a sheet and scissors. You cut two holes and then a mouth hole!!!
Thanks to Darla for this addition.