According to the official announcement, a Halloween of sort event is being introduced to CSGO which allows players to turn into ghosts when they die within the game. This new feature is available in only Casual, Demolition, and Flying Scoutsman game modes and will only be visible to players who are either ghosts themselves are observers. These Ghosts are not going to be visible to other players who are alive but this does not mean you can not haunt them. As a result, the developers have scattered interactable objects around the map including soccer balls, glass, potted plants, etc, to allow these ghosts to scare and freak players who are still alive. Those of you who are interested in the complete changes, check out the complete patch notes here.