Probably the most elusive ending in Freddy Fazbear’s Pizzeria Simulator has been the Insanity Ending. Turns out, it’s pretty easy to get once you know what to do; it’s just knowing what to do in the first place that’s the hard part.
One of the weirdest items available in Freddy Fazbear’s Pizzeria Simulator is the Egg Baby (Data Archive). This item can be bought for $6000 from Rare Finds Auction, but doesn’t appear to do anything at first. However, you’ll need to purchase this item and place it in your restaurant to get the Insanity Ending. Once you have done so, during the next night of actual gameplay, you’ll notice a very subtle difference (or rather, you won’t notice it unless you’re actively looking for it). There is a very small button right by the bottom left corner of the computer screen in your office. Normally this button is green, but upon buying Egg Baby, this button should now be blue.
If the button is blue, you are good to go. Turn off your computer. Then, with your computer off, use your mouse to click and hold this button. Keep the button held and turn the computer back on. If done correctly, you’ll see some blueprints on the screen of your computer and hear an audio file. Once the audio file has completed, you’ll be informed that you saw something that you weren’t supposed to see and that you will receive a Certificate of Insanity so no one believes your story. This certificate will hang on your game’s home menu.