Yes, there is a hidden item you can get in the shack, but you gotta have a specific quest item in your inventory for that to work first. Check the "Spoopy Secret Stuff!" sub-chapter in the walkthrough for details https://docs.google.com/document/d/1RfA3evYulYL2F-3G-RZmgUqjejens8RLvOa2mrfrsAM/...