Make a Wish. Have it horribly corrupted.

[Sizacu]

Granted, but you get tempted for slapping yourself around the face every 10 mins xD

I wish I had less hoemwork.

[Torchickens]

Granted; instead you get a truck load of coursework though, most of it is on stuff that you haven't even been taught! Then your internet connection stops working.

I wish for something to do with my old Pokémon when a new generation comes out, instead of giving my old game like 500 magikarps to bring the Pokémon over to the next game in a trade.

[Sizacu]

*doesn't even know what course work is*

Granted, but then they all turn into Magikarps! [Besides, they own x3]

I wish I had a better History teacher, who isn't strict and all.

[Avian]

Granted, but she gives you tons of homework.

I wish to become a shape-shifter.

[SilverFlame]

Granted, but you'll only get to shift into a Blobfish.
I wish I could talk to animals.That would be interesting....

[pokeman12345]

granted but they say bad things to you
i wish i had a DSi

[Pandemonium]

Granted... but they mistook it for a DSL and installed the wrong software.

I wish I was in Dublin with my girlfriend D:

[Avian]

Granted, but your girlfriend dumps you.

I wish for a chinchilla.

[Pandemonium]

granted, but it has cancer ;; (serves you right for getting me dumped)

i want a wish without a downside

[Lightshock16]

Granted but-BZZT-Compu-BZZT-Tation ERROR-BZZT-

Granted, but your downside Is nothing but a small cut on the knee.

I wish I had a social life.

[Avian]

Granted, but it's with mega nerds like me!

I wish my Chinchilla didn't have cancer. ;_;

[THE ARBITER]

granted it now has rabise an wants to bite you

i wish for a colered version of the new pokemon

[Avian]

Granted, but you never get to see it.

I wish for my Chinchilla to be immune to all diseases.

[Sizacu]

Granted, but it escapes from the Sphealrules household o:

I wish my porridge had more sugar.

[Torchickens]

Granted, however an army of ants come and steal your porridge away when you're not looking.

I wish for a level 250 magikarp called uberkarp.