If you want the absolute most simple costume, give yourself two vampire punctures on your neck. Put something on for texture first (the possibilities are endless), then color the two textured spots black and dot on small amounts of dark red until it looks like a scab. One year I did this for work and two dumb girls were baffled by it. They didn’t know if I had injured myself or if it were makeup and they were too afraid to ask. They just kept whispering about it and tilting their dumb heads until they overheard someone else bring it up.