The history of the bungee cord is a bit mysterious. Elastic cording has been used for decades for rigs used to secure luggage in vans, trucks, and even the undercarriage of planes. They were once used in parachute releases.
According to wikipedia, “The first modern bungee jumps were made on 1 April 1979 from the 250-foot (76 m) Clifton Suspension Bridge in Bristol, by members of the Oxford University Dangerous Sports Club.”
It is a little bananas to think that a similar product to one that allows you to hurtle towards the ground at roller coaster speed and snap back up through the air is available at your local hardware store. And you can make a bracelet out of it.