Conversationally, they poke, they prod, they chase. I assume this is from being educated in environments where that was the norm, and my guess that this is a style that starts in certain types of prep school (and is then imparted on the less-elite folks who attend a university with that set) is really just a guess, but there sure does seem to be a lot of correlation between school prestige and that kind of affect, in my experience, whatever the cause.
As mentioned, I have similar tendencies, but the tenacity at and commitment to this way of chatting from several elite-college folks I’ve met has been a bit much even for me—with more exposure I suspect I’d come to like it, but as it is it feels like being squished on a microscope slide, though I don’t exactly think that’s their fault and I don’t think they’re trying to give offense—but I do think the fact that it can put a person a bit off balance is part of why they’ve picked it up, it seems like a habit honed in a certain kind of affably-contentious intellectual environment (again, I’m just guessing at the causes here)