"I don't know, I've never done X before."
"Yeah, yeah. It doesn't have to be perfect analysis, just a rough idea for scheduling. Not written in stone, ha ha."
"Uh, a week?"
"Okay, great, so if I say 8 days you should have it done by then?"
"Yeah, I hope so."
"Great, thanks."
Day 3: actually doing X requires unforeseen Y and Z which will each take a month.
"We need to add Y and Z to the schedule, which will each take a month."
"There's no room for that in the schedule."
"Then I can't do X"
"We've already costed X and committed to it. We've got to do X. We need to make X happen. When can you get back to me with a path to green for X? And also, let's schedule a post-mortem to figure out why we missed on X."
At the post-mortem, PM doesn't show up: "Uh, turns out we missed on X because I estimated it too quickly and the PM committed to those estimates. I didn't know about Y and Z when estimating, and these are things I could have done to detect them as requirements if I had known to do so."
Email from PM: "Hey, could you give me an estimate for X'? Doesn't have to be perfect, ha ha."