Freddy Fazbear was after Morty Smith for revenger after the death of Rick Sanchez. In desperation to survive Morty began narrating a flashback scene, leading to a Family Guy-esque cutaway.
The cutaway opens up to a massive fleshy underwater cavern full of various animals, including massive crabs whose shells contained hollowed sections containing entire miniature ecosystems. As we explored through the cavern it was more and more obvious that this was the inside of a much larger organism. At some point a swimming centipede jumped out from a crevice and consumed my sister whole.
As we continued through we eventually found the exit where it was revealed this was the carcass of a giant duck.