I had a device for this trick when I was a kid. It was a little disc that had 12 feet or so of fishing line wound up inside. When you pulled the line out it put tension on a spring so that it would zip back inside the disc when you pressed the button on top. Just tape the end of the line to some money, hide out of view and watch the hilarity ensue. I killed so many strangers on that bridge.
Today’s Biff is heartbroken.