Make a wish about making a part of luigi's mansion like the beta and the next poster will grant it, but corrupt it and make a wish themself as well. Example:
Person 1: I wish the beta ghosts were in the final.
Person 2: Granted, but they are only in the beta gallery which you can only get to by hacking. I wish the first-person view of the gameboy horror was in the game.
I'll start: I wish the beta clock in the gameboy horror was in the final version.