In June 2007, a swing in a children’s playground was reported to the police after locals had discovered that it would move backwards and forwards non-stop on its own for ten days before stopping dead, while other swings would remain still. The police, who couldn’t conclude an explanation called physics professors into Firmat, Argentina. But by October that year, even scientists were “baffled” and could not offer a logical explanation.

Parents and children were convinced that a ghost was to blame. According to a teacher: “One child called it the Blair Witch Playground. We believe it is haunted.” Parents decided that the playground must indeed be haunted.

On April 13, 2011 episode of the Syfy Channel show, Fact or Faked: Paranormal Files, the crew went to Firmat to investigate the haunted swing. They were able to recreate the movement of the swing with a monofilament, but determined that it was not a viable hoax. Ultimately, after covering the swing with an inflatable dome and performing simulated wind tests, they determined that wind was the likely culprit coupled with the fact that the haunted swing was slightly larger than the other swings and had more surface area to catch the wind.

Source : Wikipedia