/ This is a missable trophy, and as such, you should aim to get this before going for the story-required specifics. /
This requires getting Dead Ted Edison into the human show in the future. Once you do have him registered up, instead of applying the DENTURES item, instead give him the CHATTERING TEETH.
The item known as [DENTURES] is obtained in the past by reading the textbook to the horse.
The item known as [CHATTERING TEETH] is obtained in the present by opening the ventilation grate in the party room, then chasing the teeth over into it.
The CHATTERING TEETH are required in the past for Hoagie to get the super battery, so don't give them to Washington before you use them with Laverne.