... "No well-actuallys" and "no feigning surprise."
No "well, actuallys" means you shouldn't correct minor inaccuracies in things others say when it has nothing to do with the conversation at hand. ... Programmers have a bad habit of saying, "well, actually..."
No feigning surprise means you shouldn't act surprised when you find out someone doesn't know something, even if you think it's "obvious." If someone asks, "Who's RMS?" don't say, "You don't know who Richard Stallman is?!" ...I've definitely done both of these without really thinking through the implications. I appreciate that these guys are talking about stuff like this because it's helped me become more aware of my stupidity.
I'd love to see another post where they talk more about their other social rules and what the result of implementing them has been.
Oh and if you think you'd be a good fit for Hacker School, apply for summer 2012!