I belive foxy caused the "Bite of 87".Heres my theories.
•Foxy's jaw hangs open.Unlike the other animatronics. •Foxy's sign usually says "Sorry,Out of Order!".this may be how he was punished for what he did. •Also,Foxy's sign sometimes says "IT'S ME".Maybe he's planing a nother attack against the player behind those curtains(Probably not ?) •Phone guy said "Maybe he doesn't like being watched",maybe he's saddend or embarised about what he did or how he was punished. These are my theories about the "Bite of 87".
-NightyLove1702