“World peace” always sounds so glurgy, and I don’t see it happening anyway. Someone will always come along to fuck it up. But along those lines, I would wish that everyone in the world had access to a full education. Knowledge is power. Not that everyone would use it to do good, of course. But I think things would be much better off.
“rjung screamed in agony as his eyes melted while the magic quarter shone like a million suns.”
Well it’ll either be so shiny that it blinds you, or it will fall out of the sky and hit you in the head. How’s that twist for ya?
Another possibility; your shiny quarter shows up, but with Two-Face flipping it.
I’ve seen the results of that wish before. It leads to all life being exterminated or at least all humans. Optionally a Omnipotent Totalitarian government runs every aspect of everyones life.
Remember the golden rule, be careful what you wish for.
I would wish for myself, my family and friends to be healthy, wealthy and wise.
Jim
You all get assimilated by the Borg. 
You’ll be healthy, what with all your shiny new replacement organs, you’ll be wealthy considering how many resources the Borg have, and you’ll be wise with all the knowledge of the Collective.
Yep, there is always a catch. But I do not think the Borg is quite right. Are the individual drones(?) wise or just have access to look up knowledge?
Aren’t the Borg a collective and therefore basically without wealth?
Surely oh demonic twister of wishes you can due better than a this? 
Jim
Your shapes would not be completely under control – you would shift unexpectedly at awkward times. This could even be the result
My lord, I had no idea Miss America was so powerful!
Um, since when is that the Golden Rule?
Beware the wratch of Miss America. She might smite you.
I’m not sure, but usually any discussion of wishes or stories of wishes are cautionary tales to “be careful what you wish for”.
So let me rephrase that as the Golden Rule of Wishing.
Nice question, and after giving it some thought here is mine…others will have to edumacate me about possible downside effects:
“To enjoy perfect happiness as long as I live.”
This will begin effective immediately.
It will last all the way through tomorrow…
To have a thousand dollars right about now so I can go to school in the fall.
I take it you never read With Folded Hands, about the robots who were programmed to maximize human happiness. They’d make you happy all right - with brain surgery, if necessary.