Okay… so I’m kind of surprised that this hasn’t been a forum game yet… but the way it works is:
No wishing for infinite wishes, or wishes without drawbacks.
Here’s an example:
I wish for a cookie!
Wish granted, but the cookies are burnt.
I wish for a car!
So yeah… I’ll start us off!
I wish for cake!
Granted, but it is poisoned!
I wish for the 234th annual Saddam Hussein Hunger Games to be canceled due to Narnian Farts!
Granted, but the farts aren’t Narnian.
I wish for Swift_Cube to not wish for such out-landish things!
Wish granted, but the smelliness spread into the real world, too…
I wish for a giant rocket to be shot at Pluto!
… and it’s done, but NSwift_Cube has in anger set a nuclear attack on your house.
I wish for… real Pokemon.
That’s been done before, so your wish is granted, but they all ended up sucked into and trapped in an alternate 8-bit world of monochrome.
I wish for my house to be rebuilt.
Wish granted, it’s a box.
I wish for more cake!
Wish Granted, but now he is Fascist!
Whelp. That’s not good. Soooo…what do you wish for? 
Wish granted, but it isn’t granted because you didn’t wish for anything.
I wish for my forum game to reach 1,000 posts!
Granted, but your wish doesn’t work.
I wish for one of those things that go under your username, for example, “Voxel Novice”
Granted, but it is “The Inferior Dwarf”.
I wish for one of those things that go under your username too! Except it says “Starbound Server Host”.
Wish granted, but it says “Starground Berber Grossed”.
I wish for a set of Diamond armor in Starbound!
Granted, but instead of “Starbound Server Host”, it says “The Village Idiot Of The Forums”
I wish for nothing bad that will corrupt my wish.
Wish not granted, because you got ninja’d.
I wish for Dwarves to be forever cursed with the inability to become ninjas.
Wish Granted, But Austrians are Germans… lol