The Nerf ball, it turns out, was invented one day entirely by accident.

Guyer says he had a team of "five or six" toy engineers working on a concept for a stone-age-themed game. The idea was this: several players would be walking around a game area with a bunch of foam rocks between them. Underneath the rocks would be some sort of loot—"maybe funny money or something." The point of the game was to try to prevent the other players from stealing the loot. Each player would be armed with a foam bat, and would smack anyone who tried to steal the loot.

"One of our people began to take a piece of foam rock and started throwing it in a net," Guyer recalls. "Then the rest of us began cutting smoother rocks and bouncing them around."

"And then we realized that we had something that was substantially better than our original idea."