"Google it" is usually the best response for most situations where the phrase is used. Most questions you could ask have already been asked, often on the very forum you're asking it on. Why should anyone take the time out of their day to answer a question you already have the tools you need to answer it yourself? You say it's rude, but isn't demanding that someone else do your leg work for you even more so?
Now sometimes it isn't an appropriate answer, such as when asking for advice on something specific and complicated, such as coding, or something subjective, such as philosophy or personal situations. But even then, you should do the courtesy of searching the forum(especially if it's a forum specializing in the subject you're asking about) to see if there is an existing topic that either answers your question or is related and still active. Otherwise you might get a "RTFF" instead.
Basically, as the person imposing on others, the burden of courtesy is on you. Some questions just have to be asked, but you shouldn't expect people to indulge you when you inquire into the whereabouts of the chair sitting next to you.