Symptoms of the Operator Symbol include: weevil attacks, intense ice cream headaches, and treefingers.
The Operator Symbol is associated with the Slender Man. According to some sources, it's a repellent against Slendy. Other sources say that it actually attracts him. Even otherer sources say that the symbol is a memetic device that causes us to think about Slendy and thus attract his attention.
Whether using the Operator Symbol is a good idea or a bad idea, the fact is that it shows up in a whole lot of places near the Slender Man. And now you know -- and knowing is half the battle. (The other half involves an inordinate amount of violence, so just stick with knowledge for now.)