I dressed up in a headless costume, inspired by ideas from this website.
I used a kid-sized roller bag and cut away most of it (including the wheels) so that only the handle and the part that goes against the back remained. Using duct tape I secured the handle up in place, and attached a hanger to the top part of the handle, also with duct tape.
I could tell you how I made the rest of the costume step by step, but I think it can be done in many ways and just requires resourcefulness, and in my case, a lot of duct tape. Big tips: buy a very very long dress or shirt with buttons down the front, so that the head can stick out between buttons and you don’t have to cut a hole; also, a jumpsuit (my first attempt) doesn’t allow for flexibility with the height so avoid my mistake and just go with a dress or shirt (nothing with pants), the longer the better. Also the neck was a challenge for me, so I recommend buying pre-bloodied gauze at a Dollar store and not bothering with making your own fake neck and blood.