I've got a few responses on automatic. Why aren't you married - I haven't met the right person yet. How much money do you make - Enough to support my lifestyle. What is your sexual orientation - minkey starts throwing punches.

When working in customer service, you're just going to have to suck it up sometimes and refrain from calling someone a moron (depending on exactly how obnoxious the question asked was). Even outside of work, depending on the situation, it has the added benefit of hopefully showing the person never to ask that kind of question again. Like when some guy asked the person next to me if I spoke English, and I replied, Yeah. Why? (for those who don't know, my parents are Chinese, I was born & lived my entire life in the US. I can barely speak Chinese.) The guy didn't MEAN to be obnoxious, but he looked pretty embarrassed when he found out that the asian chick could hear him. Chances are, he'll think twice before assuming again.

When someone asks an obnoxious or stupid question I have found that if I answer it by talking excessively, go on and on and on and give them far more information than they ever expected (or wanted), they are usually the ones to end the conversation. It also discourages them from asking any additional questions.