The sandwich appears in front of you, but you're unable to eat it while constantly thinking about it, and you die of starvation.

I wish for a bunk bed.

You get one, but trying to sleep on both beds at once causes you severe back problems.

I wish this thread was funny.

Your wish for the thread to be funny is fulfilled. It in fact becomes so funny, that when one of the devs of SSF2 reads it, he/she can't stop laughing for days on end and therefore can not continue work on SSF2. Before the whole project gets derailed, the rest of them decide that this thread is TOO funny. As a result, the thread gets locked, and humor is banned across the forums. Forever. This place becomes so boring that people prefer to lurk elsewhere. The forums die, SSF2's fanbase dies with it. Version 1.0 is never released. The end.

I wish I had a functional extra pair of arms.

You get an extra pair of functional arms, but they turn sentient and reject you.
They overpower your normal arms and choke you to death.

I wish this one girl at my school would notice I like her.

She does, but doesn't like you back. She then proceeds to do everything she can to make you like her more, while continually rejecting you.
Eventually you go crazy and in a flurry of rage, let your magic powers go wild. The kingdom you so loved is destroyed in an instant.
Seeing you in your current state, your sister confines you to a floating island where you are killed by a robot with funny ears.

The end.

I wish for another sandwich.

That sandwich is actually an extraterrestrial being that looks like a sandwich, and eats you alive.

I wish that SSF2 0.9 would be released in December.

Oh, it gets released in December, but it is, in fact, a leaked copy. Said copy is actually a virus that takes over the downloader's computer, stealing all your personal information discreetly while at the same time using your computer's resources to spread the virus to others. Not only do hundreds--even thousands--of people have their identities stolen, but the virus falls into the hands of Chinese hackers. These hackers modify the virus and actually take over the internet... briefly. Not wanting to have all the internet dominated by dangerous hackers, the US government pulls out their ultimate contingency: They nuke the internet itself! The internet is no more, and as technology advancement grinds to a halt the world is thrown into utter chaos. But hey, you got to play SSF2 0.9 early. It was worth it.

I wish I was better at SSF2.

You resort to liberally using Ichigo's Uair against BM, effortlessly defeating opponents. However, everyone screams at you for being uber-cheap.

I wish that Mg Mafia would end sooner.

It doesn't.
I wish I could read minds.

The government finds out about your ability and brings you into Area 51 for dissection. They overdo it and you explode, plunging the entire world into oblivion with you.

I wish that books could become worms.

I see what you did there.

Books become worms that eat you.

I wish Romney was elected instead of Obama.

He gets elected, but ruins the country because he's a terrible president.

I wish every state legalized marijuana.

It leads to Americans becoming extinct, due to "accidents".

I wish I knew how keyblade did not get banned already.

You find out he was banned for a week, but he got angry and got to your house and he saw*
*OPEN WITH CARE
and ran away

I wish Ya Dad would put up a livestream this saturday