The rules are simple:

Person X makes a wish.

Person Y responds by granting the wish, but corrupting it to the point that it's no longer desirable.
Person Y makes a new wish.

Example:

Chef Boyardee wrote:

I wish for spaghetti.

John Romero wrote:

Granted. You are force-fed spaghetti until you die.

I wish I had a haircut.

etc...

I'll start:

I wish I had a Voodoo 5 6000.