Make a Wish. Have it horribly corrupted.

[Caldoran]

Granted, so you would instead be locked in a dark cardboard.

I wish I could fast forward time.

[OpalRhea]

Granted, but you vanish from the timestream therefor mking your ability useless.

I wish I could shapeshift into fantasy creatures

[master1]

Granted, but you get carted off by the government for testing and dissection.

I wish some of the Greek myths and legends were real. =)

[Massacre\\♥]

they are.
but then one of the mythical creatures eats you. DD;
and the rest eat everyone else.
phahahah, i dunno. x)

i wish i could meet justin bieber. <33

[Angelpants.™]

Granted, but afterwards he'll admit to you that he has feelings for your mother.

I wish I had a puppy!

[master1]

Granted! *Cerberus appears* =D

I wish I was taller.

[Alexi: Crazier by the Day]

Granted, but you become so tall you always hit your head when entering a room.

I wish the Percy Jackson series was real.

[Z:illyhoo]

Granted, but you will become the victims of all those demons and monsters. (It's not that fantastic. =])

I wish I had a small dragon for a pet.

[Alexi: Crazier by the Day]

Granted, but you will become the victims of all those demons and monsters. (It's not that fantastic. =])

Whats not fantastic? The series? I like it a little, but being the daughter/son of a god would be cool in my opinion.
About your wish...
Granted, but it burns you to a crisp.

I wish I could go to a party.

[MOP]

Granted, but it's a party for Aztec Gods and you're the sacrifice.

I wish...I was a women!   

[master1]

Granted, but you get pregnant by rape.

I wish I could make my mind up about evolving into Croconaw. D:

[Spook]

Granted. You decide not too but then someone asks to trade a legit level 1 Arceus for a Croconaw. They wont wait and leave you empty handed.

I wish I could have a pet Arceus

[MOP]

Granted but it creates a new universe without you.

I wish I never had to go to the toilet again.

[Spook]

Granted. I un-surgically remove your bladder and stomach. Have fun.

I wish I could get Batman : Arkham Asylum for mah Xbox360

[master1]

Granted. *exchanges your Xbox360 for the game* =)

I wish I was slightly more amazing.