Why does anyone say "You're kidding!"? It's used farrrrr out of proportion to people actually kidding (though I can imagine hilarity resulting if reporters all start saying it during a politician's press conference). Maybe the someone-taking-time-to-tell-you-somethin
Seriously. I think about this stuff.
(I'd also go on about the phrase "pretty much," but I've already done my blathering about that...)