x's are kisses because the illiterate in the middle ages weren't able to write, even their own names. So when they would sign a contract, they would just make an X and kiss it for good luck. o's are hugs. I don't know where that came from.
__________________
Penguin dust, bring me penguin dust, I want penguin dust--
really, think about it, everyone always orders it with "XO" and then they translate it with "hugs and kisses" so it's only logical that they corespond to each other.
__________________
I'm a man who fucks with fire. I'm a man who sleeps with liars, but I don't come from Hell, no. I wasn't raised in Hell.