You looked at the title of this post, and immediately understood the question. You didn't have to look up to find out what's up - because you knew the question was not really about space.
Most of the time, most of the people reply something like "not much." They think the question means something like "what's going on?" or "what's new?"
If they looked up, they would see that there is lots going on above them. If they were lucky, they would see someone climbing above them who would offer a model of how to get up. Or maybe they would see that the rocky patch they are climbing leads to some wide, carved stairs and a glorious view.
What's up? Are you?