You didn't know about this (FNAF 1)

Display of the easter egg
Try to go to the stage cam, you will see the robots playing the show, but sometimes, you will see freddy staring at the camera!

Why would they do that?
Well, freddy is trying to unlock the door by staring at the camera to see what your doing!

How we survive the easter egg?
Try to not open both of the doors or freddy will come in, you can check at the cam of the stage to see if he still playing the show.