Here’s how the method works: Tying String Around Your Finger Will Help Get Rings Off That Are Stuck.
Essentially, you wrap the elastic band (oxygen mask strap in the video) tightly around the finger, moving toward the ring as you go. Once you get to the ring, try to feed the band through the ring. Once you do, you should be able to start unwrapping the elastic and it’ll bring the ring with it. Check out the video to see it in action.