Green Gobblin' Trophy in Back to the Future - Episode 5: OUTATIME
Treated Desert Edna to an algae cake.
How to unlock Green Gobblin'
*Missable* When back at the Expo, after leaving the House of the Future, Trixie will pull the "Hostile Guy" on stage to talk about his algae cakes. While he is there, go back to his booth and steal the box. Now, once you are at Edna's house in the alternate 1931, in order to coax her out of her house, you will need to tell her you brought her something. When she asks what you brought her, open up your menu and equip the algae cakes, and interact with Edna. She will come down and take them, and your trophy will unlock.
For more information, refer to the trophy walkthrough under "The Future isn't Written ".