1987.

Backstory.

After a bit of thinking I kind of realized that this story would make sense to some but not to most of them, so in your favor I decided I shall do some explaning of the whole entire thing.

So...this story surrounds around the popular horror game Five Nights at Freddy's where you are basically a nighttime search guard who watches over the animatronics at the popular pizzeria Freddy Fazbear's Pizzeria. You are to avoid letting the animatronics get to you so they will not stuff you in an empty Freddy suit. Basically, in their minds you are an endoskeleton out of costume and they are to put you back in. In that suit (which is full of wires and such) you pretty much die and the game is over. As days progress it gets more intense. The animatronics you attempt to avoid is Chica the Chicken, Bonnie the Bunny, Foxy the Pirate, and Freddy Fazbear (the bear obviously). You are to survive five nights with limited power, a paneramic view from a monitor, lights to each hall and doors for limited protection. 

So the Bite of 87 is an incident that was mentioned by the guy on the phone the first day as a nightguard on FNAF. Because the employees at FFP were afraid that the servos of the animatronics would lock up, they were allowed to roam freely during the day. During one of their free roams one of the animatronics attacked someone and took out their frontal lobe. That incident caused a major drop in business due to safety concerns. Details of the attacker and victim are not known. Foxy was thought to be the one who made the attack due to his jaw hanging loosely which was most likely due to extensive force. Also, his area, Pirate's Cove, was out of order which could have been due to the incident making the area shut down. His teeth are also broken and sharp. Freddy was also a culprit due to one of the rules stating that people are not to touch Freddy (located in the East Hall, I believe). There were also faint handprints on his face which could signal struggling in some fashion during the bite. 

I am not fully sure on what happened and I do not know if I will ever know, but these are theories and hopefully you will enjoy the story coming up! (Shoutout to my English teacher who may be reading this if she did not forget :)