Bite of 87

Uhh... they used to be allowed to walk around during the day too, but then there was The Bite of '87. Yeah. I-It's amazing that the human body can live without the frontal lobe, you know?

The bite of 87 is an incident happened some time in the year 1987. The accident is happened in Tiwa's Pizza and caused by someone, possibly a robot. It's about maybe a robot bite a victim from it's frontal lobe and losing it. It's still unclear who is the cause of it, who is the victim and the victim is still alive? According to the Phone Dude, the victim might had died by this bite, or maybe luckily survived without a frontal lobe.

Unlikely Robots
Rosary and Yuri from both games might had been unlikely for the bite, due to them having no sharp teeth, even if Rosary has two sharp teeth, the victim is not badly injured or maybe not injured at all. Mariona is also out of the list, due to her being almost blind for the whole second game.

Mei Hua
Mei Hua is theorized for the candidate for the bite by fans. Due to her being tattered in both games. Also, her home Pirate Cove from both games has a sign "Sorry Out of Order!", this sign might had been added to the Pirate Cove to show that customers cannot be too close to her or another bite will be caused. Also, Mei Hua hides from the others, maybe she is too scared to cause another bite for the player.

Tiwa
Tiwa has an invisible mark on her face, as the handmark can only be seen when you brighten her face up. This theory is proposed by a lot of fans who theorized Tiwa is the candidate. The hand mark might be caused by the victim who is going to get bitten by her by pushing Tiwa back for preventing, but it didn't turned out and ended up losing its frontal lobe from Tiwa herself. Also, in the East Hall corner, a rule list is visible, and in the rule list has a rule said "Don't Touch Freddy". As we all know, Tiwa is processed by Freddy, and maybe this rule is added after the bite had been created.

Nil
This theory is not really so popular, but some fans think that Nil is the cause for the bite. Since he is the only robot represents a cat, it is possible that he bites a tiny part from the frontal lobe.

Peter Painter
Since Peter Painter is the security guard for both games, Phone Dude says that he is responsible for a birthday party in the last night in the second game. Phone Dude also says that he must stay close to the robots, and make sure that none of them hurt Peter.