A semi-flat stick with a thread sized-length loop thru a hole at one end, too short to pass over the stick's opposite end, say, loop can be stretched 95% to stick length. By passing the loop through a button-hole and scrunching material, it's possible to loop it around the button-hole. Can be maddening to first time victims. Easy to make. I've witnessed "This is impossible!" more than once.
I wish we had a wise-old hacker Bill curmudgeon in the neighborhood.