This is a spectacularly ill-posed question. For one thing, it seems to blur the distinction between morality and values in general, by asking such questions like "Would you stay in bed because there was no reason to get up?" What does that have to do with morality?
When you get rid of a sense of values, the result is clinical depression (and generally, a non-functional person). When you get rid of a sense of morality, the result is a psychopath. Psychopaths, unlike the depressed, are quite functional.
So the question reduces to, what would you do if you were a psychopath? This is perhaps interesting to think about, but hard to answer, since most of us are not psychopaths and find it extremely difficult to imagine what it would be like to be one. And if you were one, you wouldn't be you, since the fundamental structure of your personality would be vastly different.
To those who say "Nothing is real," I once replied, "That's great, but how does the nothing work?"
Suppose you learned, suddenly and definitively, that nothing is moral and nothing is right; that everything is permissible and nothing is forbidden.
Devastating news, to be sure—and no, I am not telling you this in real life. But suppose I did tell it to you. Suppose that, whatever you think is the basis of your moral philosophy, I convincingly tore it apart, and moreover showed you that nothing could fill its place. Suppose I proved that all utilities equaled zero.
I know that Your-Moral-Philosophy is as true and undisprovable as 2 + 2 = 4. But still, I ask that you do your best to perform the thought experiment, and concretely envision the possibilities even if they seem painful, or pointless, or logically incapable of any good reply.
Would you still tip cabdrivers? Would you cheat on your Significant Other? If a child lay fainted on the train tracks, would you still drag them off?
Would you still eat the same kinds of foods—or would you only eat the cheapest food, since there's no reason you should have fun—or would you eat very expensive food, since there's no reason you should save money for tomorrow?
Would you wear black and write gloomy poetry and denounce all altruists as fools? But there's no reason you should do that—it's just a cached thought.
Would you stay in bed because there was no reason to get up? What about when you finally got hungry and stumbled into the kitchen—what would you do after you were done eating?
Would you go on reading Overcoming Bias, and if not, what would you read instead? Would you still try to be rational, and if not, what would you think instead?
Close your eyes, take as long as necessary to answer:
What would you do, if nothing were right?