Nothing quite so vexing as when people who know nothing, or very little, about publishing try to give you tips about the process to try to be "helpful." The following is a conversation I had a dinner:

Random Dude A Who Sat Down At Our Table: "I think if you have a few chapters, you can submit them to the publisher and they'll tell you if they want you to finish the manuscript."
Me: "...No you can't. At least not in fiction. And certainly not for an unpublished writer. You need the full manuscript, yo. And who submits directly to publishers these days anyway? Agents, dude." (Okay, I didn't actually talk that way. That's my revisionist head voice version.)
Random Dude A: "Uh, yeah, I think that sounds right."
No, really?
Random Dude B: "How do you know this? Have you gotten in contact with publishing people already?"
It's called the Internet. Seriously.)

And particularly vexing, I say, because I don't have the patience for such useless chit chat when I haven't yet started writing the 10-15 page paper on Confucius and Mencius due the next day.