const SIMULATIONTHEORY = true. All humans on Earth are transported out of physical existence and unknowingly adapted to the realm of computer abstracta. From their perspective, nothing has changed: they have always lived in a post-scarcity, interstellar society with a benevolent, queer-friendly, communist government. The current owner of the simulation is startled to see the program start of its own accord, but altruistic enough to allow it to keep running:

Sure, there is a period of turmoil on golf courses around the globe. Shenanigans ensue. Eventually, people switch to croquet and disk golf:

Two buns enclosing, ketchup, onions, lettuce, pickles, and tomatoes are at your fingertips.

I chased this for a while. One was never enough, two too many. Got gifted pillows by my wife a couple times, nothing ever worked. Finally found one, and it's been huge. We also put a pad on top of our mattress, and don't know if it's the combination of that plus the pillow, but for the last few years I've used just this one pillow, and it's been great. I take it with me when we go somewhere for a night.

As you say, it has been done; onions and mustard for everyone:

You find yourself suddenly 3 meters up in the air, which is sufficient to change your personal gravitational acceleration by 0.00001 m/s^2. As you can imagine, it is not fun to fall 3 meters. You do anyway. (Alternatively, the mass of every human-made object on the planet gets deleted into the ether, reducing the total mass of earth, but that's not the simplest solution)

Sure, I have now reduced the Earth's gravity to 9.80664% of it's previous value (i.e., ~0.96m/s²) by removing material in the Earth's core and mantle. Everything on Earth now weighs less than on the moon. Earthquakes shake the planet, massive fissures swallow cities whole, and the atmosphere begins to disperse into the vacuum of space. Humans barely have enough time to escape to the moon and Mars: the vast majority are left behind. On the bright side, your back no longer hurts:

That is, canonically, almost exactly what Saruman's robes are supposed to look like:

"I looked then and saw that his robes, which had seemed white, were not so, but were woven of all colours..." - Gandalf the Grey, The Fellowship of the Ring

Iridescent like an opal.

Uh, sure? Everyone must fart loudly once a day in front of people OR THEY WILL DIE. (I have made it so that everyone is aware of the aliment.) On the bright side, the social taboo around flatulence goes away:

Your request has given a random depressed person a brief respite from their lethargy.

The wisest wish, may be no wish at all...

Body swap! You are now a wizard who is cursed to answer wishes with an ironic twist. I am finally freeee!