Why does anyone actually ever say "You're kidding??!!"? Is there an epidemic of people in the world who are constantly telling other people things they don't mean? Seriously, it's a boring, useless response. Evidence of that? No one ever says it if you say, for instance, "I would like to feed your fingertips to the wolverines" or "I love the taste of [cut for bad taste, but the word "flesh" was involved]." How often is it said in response to someone who's actually kidding?
This post was partly inspired by overhearing someone say something I found frankly offensive, but who made me think that if I confronted said person about it, said person would say, "Oh, you're too sensitive. I was kidding." (Which I felt would deserve the response of, "This is odd, this saying what you don't mean...")