Hackish speech generally features extremely precise diction, careful word choice, a relatively large working vocabulary, and relatively little use of contractions or street slang. Dry humor, irony, puns, and a mildly flippant attitude are highly valued --- but an underlying seriousness and intelligence are essential. One should use just enough jargon to communicate precisely and identify oneself as a member of the culture; overuse of jargon or a breathless, excessively gung-ho attitude is considered tacky and the mark of a loser.
This speech style is a variety of the precisionist English normally spoken by scientists, design engineers, and academics in technical fields. In contrast with the methods of jargon construction, it is fairly constant throughout hackerdom.
It has been observed that many hackers are confused by negative questions --- or, at least, that the people to whom they are talking are often confused by the sense of their answers. The problem is that they have done so much programming that distinguishes between
if (going) {
and
if (!going) {
that when they parse the question "Aren't you going?" it seems to be asking the opposite question from "Are you going?", and so merits an answer in the opposite sense. This confuses English-speaking non-hackers because they were taught to answer as though the negative part weren't there. In some other languages (including Russian, Chinese, and Japanese) the hackish interpretation is standard and the problem wouldn't arise. Hackers often find themselves wishing for a word like French `si' or German `doch' with which one could unambiguously answer `yes' to a negative question.
For similar reasons, English-speaking hackers almost never use double negatives, even if they live in a region where colloquial usage allows them. The thought of uttering something that logically ought to be an affirmative knowing it will be misparsed as a negative tends to disturb them.
Here's a related quirk. A non-hacker who is indelicate enough to ask a question like "So, are you working on finding that bug *now* or leaving it until later?" is likely to get the perfectly correct answer "Yes!" (that is, "Yes, I'm doing it either now or later, and you didn't ask which!").