You grant the previous poster's wish, corrupt it, and make your own wish.

I wish I had infinite grilled cheese sandwiches.

Granted, but they're poisonous.

I wish I was a millionaire.

And so on.

I wish I was a toucan.

you're captured and have to do cereal commercials

i wish i could fly and also fly super fast at very high speeds, come ruin my dreams minus world

you can fly but you fly so slowly that it would take you until the heat death of the universe to raise yourself more than a few inches off the ground. your super fast flight on the other hand is so fast that your body cannot take the strain and you fuckin die from various effects it causes

i wish that symphogear gx didnt fucking suck so bad

woosh! its good now but you have small penor

i wish all my teeth were razor sharp

Granted, but they hurt real real bad!

I wish I had laser vision.

granted, but you can't turn it off and it hurts really, really bad.

i wish for world peace.

world peace is achieved in that no one is alive anymore

i wish that i had a better idea for a wish

you use experimental radiation to inject a better wish idea into your brain, unfortunately you develop a brain tumor

i wish i could run really fast

you run really fast but you cant stop

I wish for more wishes

granted but you can only use your wishes to wish for even more wishes and nothing else

i wish that i had a nice wardrobe

Your very nice wardrobe has a portal to Narnia in it, unfortunately Aslan eats you

I wish for a new pair of socks

granted, but they're already used and there's this weird crusty feeling about them...

i wish that i could be able to make my own godzilla movie.

granted but you have to do a porn parody

i wish i had a switch

Granted, but your Joy-cons are really loose

I wish I was attractive

you're attractive... to bullets, not in looks. good luck

i wish that i could speed up and slow down time.

You can speed up and slow down time but you cannot return to the normal flow of time ever again.

I wish Fun with Despair was a moderator on Minus World.

that wish is already corrupted

i wish that i won a $5000 clothes shopping spree

granted, but the money used for all your clothes was stolen from a charity.

i wish that i could start using proper punctuation.

Boom! Your punctuation is on point - in latin.

I wish I had 1,000 more kitties.

granted, RELEASE... THE KITTIES!

i wish for more free time.