For instance that the world splits and that in one world the cat is alive and in the other the cat is dead. In one world you'll observe the cat being alive and in the other world you observe the cat as dead. Both worlds are equally real and in both worlds you have the sensation of being in the only real world.
Don't take the "splitting" too literally either. Otherwise you've merely replaced the problem of when a wave function collapses, with the problem of when the worlds splits.
The collapse of the wave function is, as far as I understand it, conjured up because the idea of a single world appeals to human intuition (even though there is no reason to believe the universe is supposed to make intuitive sense). My understanding is that regardless of the interpretation you put behind the quantum measurements you have to calculate as if there are multiple words (i.e. a subatomic particle can interfere with itself) and the collapse of the wave function is something you have to assume on top of that.
8 minute clip of EY talking with Scott Aaronson about Schrödinger's Cat
Suppose you believe in the Copenhagen interpretation of quantum mechanics. Schroedinger puts his cat in a box, with a device that has a 50% chance of releasing a deathly poisonous gas. He will then open the box, and observe a live or dead cat, collapsing that waveform.
But Schroedinger's cat is lazy, and spends most of its time sleeping. Schroedinger is a pessimist, or else an optimist who hates cats; and so he mistakes a sleeping cat for a dead cat with probability P(M) > 0, but never mistakes a dead cat for a living cat.
So if the cat is dead with probability P(D) >= .5, Schroedinger observes a dead cat with probability P(D) + P(M)(1-P(D)).
If observing a dead cat causes the waveform to collapse such that the cat is dead, then P(D) = P(D) + P(M)(1-P(D)). This is possible only if P(D) = 1.
If you don't say that only conscious agents can collapse waveforms, then you have to agree that something in the box collapses the waveform as seen from inside the box, while it's still uncollapsed to Schroedinger. And Schroedinger's opening the box collapses that waveform for him; but it is still uncollapsed for someone outside the room. This seems like it might be equivalent to many worlds - all possibilities already exist; you just haven't chosen which one you're going to access until you open the box.
But if you do say that only conscious agents can collapse waveforms, then it's something about their mental processes that does the collapsing. This could mean their beliefs matter. And then, the cat is always dead.
ADDED: People. Read the entire post before responding. I am not claiming that the cat is always dead. I am not claiming that consciousness collapses waveforms. I am claiming that there are only 2 known alternatives:
If you can't produce another alternative, and you don't believe in many-worlds, you owe me an upvote.
Finally, this post is supposed to be fun! You are crushing all whimsy and playfulness on LessWrong when you pile downvotes like bricks on anything playful because it does not provide a complete and satisfactory resolution.