Ok, basically, you have to grant someone's wish and then destroy it. For those of you who've seen Beddazzled, that's the reference.
Example:
Player X: I wish I had a goat.
Player Y: Granted, but the goat is on its deathbed.
I wish I had an Xbox
Player Z: Granted, but it has a PS2 hard-drive.
I wish... etc.
So I'll start.
I wish I had a new Ferrari.