TOTALLY there with you! I'm the same way. Being female, I want to scream every time someone insists I smile more! Why would I go around grinning like an idiot all the time? I'm not miserable (not always, haha), but I am very thoughtful (perhaps "too much" so, I guess) and there is usually SOMETHING on my mind, even if it's a pleasant thing, I'm probably thinking REALLY HARD about it. So I get told I look angry all the time.
I also love British humor (God Save Stephen Fry and John Cleese) and tire of schlocky, over-the-top crap that often passes for American "humor" (or at least sitcoms). Notable exceptions are Bill Hicks, Richard Pryor, and early George Carlin. And Demitri Martin! yay! 