There is an ancient and hallowed tradition: if you get a reply that reads “RTFM”, the person who sent it thinks you should have Read The Fucking Manual. He or she is almost certainly right. Go read it.
RTFM has a younger relative. If you get a reply that reads “STFW”, the person who sent it thinks you should have Searched The Fucking Web. He or she is almost certainly right. Go search it. (The milder version of this is when you are told “Google is your friend!”)
In Web forums, you may also be told to search the forum archives. In fact, someone may even be so kind as to provide a pointer to the previous thread where this problem was solved. But do not rely on this consideration; do your archive-searching before asking.
Often, the person telling you to do a search has the manual or the web page with the information you need open, and is looking at it as he or she types. These replies mean that the responder thinks (a) the information you need is easy to find, and (b) you will learn more if you seek out the information than if you have it spoon-fed to you.
You shouldn't be offended by this; by hacker standards, your respondent is showing you a rough kind of respect simply by not ignoring you. You should instead be thankful for this grandmotherly kindness.
If you don't understand the answer, do not immediately bounce back a demand for clarification. Use the same tools that you used to try and answer your original question (manuals, FAQs, the Web, skilled friends) to understand the answer. Then, if you still need to ask for clarification, exhibit what you have learned.
For example, suppose I tell you: “It sounds like you've got a stuck zentry; you'll need to clear it.” Then: here's a bad followup question: “What's a zentry?” Here's a good followup question: “OK, I read the man page and zentries are only mentioned under the -z and -p switches. Neither of them says anything about clearing zentries. Is it one of these or am I missing something here?”
Much of what looks like rudeness in hacker circles is not intended to give offense. Rather, it's the product of the direct, cut-through-the-bullshit communications style that is natural to people who are more concerned about solving problems than making others feel warm and fuzzy.
When you perceive rudeness, try to react calmly. If someone is really acting out, it is very likely a senior person on the list or newsgroup or forum will call him or her on it. If that doesn't happen and you lose your temper, it is likely that the person you lose it at was behaving within the hacker community's norms and you will be considered at fault. This will hurt your chances of getting the information or help you want.
On the other hand, you will occasionally run across rudeness and posturing that is quite gratuitous. The flip-side of the above is that it is acceptable form to slam real offenders quite hard, dissecting their misbehavior with a sharp verbal scalpel. Be very, very sure of your ground before you try this, however. The line between correcting an incivility and starting a pointless flamewar is thin enough that hackers themselves not infrequently blunder across it; if you are a newbie or an outsider, your chances of avoiding such a blunder are low. If you're after information rather than entertainment, it's better to keep your fingers off the keyboard than to risk this.
(Some people assert that many hackers have a mild form of autism or Asperger's Syndrome, and are actually missing some of the brain circuitry that lubricates “normal” human social interaction. This may or may not be true. If you are not a hacker yourself, it may help you cope with our eccentricities if you think of us as being brain-damaged. Go right ahead. We won't care; we like being whatever it is we are, and generally have a healthy skepticism about clinical labels.)
Jeff Bigler's observations about tact filters are also relevant and worth reading.
In the next section, we'll talk about a different issue; the kind of “rudeness” you'll see when you misbehave.