I don't have _a_ most worthless meeting. I have a template. We have meetings like this frequently:

"Customer wants x, y and z done"
"Ok, do we have a data spec for x?"
"Not yet"
"Do we know what the output for y will be?"
"No, still in development"
"We can't really do z yet until we know more about x and y"
"True"
"Deadline?"
"Next week. Or sooner. Maybe later. We don't know yet"

At this point I usually think: And we're meeting now...why?