Footbag was invented in Oregon, USA, when athlete John Stalberger met Mike Marshall, who had been kicking around a hand-made bean bag. John had recently had knee surgery and was looking for a way to work on his flexibility.
He instantly took to the game and become good friends with Marshall. They called the game, "Hack the Sack".
The game took off in England as parents realised they had at last found a football substitute that would drastically reduce the number of broken windows, flattened hedges and irate neighbours they suffered.
Hacky sacs came in a variety of colours and were made from a variety of canvases and plastics, which were more or less liable to split and spill beans over the carpet. The craze began to fade in the mid 1970s.