Pop-pop snappers, also known as "Bang Snaps," are generally considered safe if used properly. They consist of small paper-wrapped packages containing a small amount of silver fulminate or gravel coated in silver fulminate. When thrown, they make a small popping sound.
However, it's important to follow the instructions on the packaging and not to throw them directly at people or animals. Ingestion or inhalation of the contents could be harmful. It's also important to store them in a safe place, out of reach of children and pets.