The rules are simple enough:
Poster 1 is Goomba.
Poster 2 writes a fanfic about Goomba and Sonic, eg.
Goomba and Sonic locked eyes from across the room. They made their way to each other's embrace, or so they thought. They failed miserably but didn't mind, for a Goomba has no arms. Goomba turned to Sonic and whispered "I can't, Senpai". Sonic smiles and says softly " You needn't arms to touch my butt." Then they rode off on Tails into the sunset and had 12 children.
Then, Poster 3 writes a fanfic about Poster 2 and Sonic.
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Sounds easy enough, right? Let's start!