What about using a toothpick to open it? Wooden or plastic it won't get detected at the scan. Just a thought other than that I can't think of anything other than maybe a condom but dont tie it just twist it off then rubber band it. With the rubber band though tape one end of it to the side of the condom with gorilla tape that way it doesn't fall into the toilet when off. MUST BE GORILLA TAPE... I know that sounds odd but trust me it will hold the best much better than duct tape. Best of luck.