See, ever since I learned in French class that most of the worst swears in French involve curses on the church and holy things, I've sort of paid attention to the way you can learn something about a culture by what people talk about when they hit their thumbs with hammers. While France today is fiercely proud of being intentionally secular, the fact a lot of French curse words invoke God, hell, church-doors and such, gives an interesting clue to French heritage, and the development of the language.
Conversely, most of the English swears that are used most often, and considered most crass, involve body parts, and body functions. I'm not going to list them off here, but you know the ones. (Swears on the comment board for this page shall remain up only if they are discussed academically, rather than simply posted for the fun of writing potty mouth on the internet, thanks.) I think those very bawdy words provide an interesting clue to understanding the focus on things, and a tendency toward materialism evident in English speaking cultures.
I asked Girlfriendoseyo about this once -- Korean culture developed in a very different place and along very different lines than them western cultures, and asked her, not to rattle off all the Korean swear words she knew, and teach them to me, but to clue me into the general subject matter of Korean curses.
She said that most curses in Korean involve bringing someone down -- calling somebody a wiener-suckler (you know the word I mean) or an Oedipal-incest-practitioner (you know the word) is about as harsh as you can get in English, and crazy's pretty mild (maybe a 3 out of 10) but in Korean, the word crazy is an 8 out of 10 -- the simple word "crazy" in Korean is a bit English to calling somebody "totally batshit in-'f-word'ing-sane" in English. In Korean, Girlfriendoseyo told me that the most commonly used words bring a person's status low -- you're a dog, an idiot, you're a fool, you're dirty and low -- that's the general gist of most Korean curses.
(comic by xkcd.com)
"But Girlfriendoseyo," I interjected, "from what I know about Korea, and Korea's emphasis on filial piety and family obligation, wouldn't the worst swears in Korea involve insulting somebody's family? Wouldn't "your mother wears army boots" be more offensive to a Korean than "You sleep in a gutter"?
She flashed me a "oooh, careful, buddy!" face, and said, "Yeah. It would be. But if you insulted a Korean's family, it would be war between your families."
That's right. Family loyalty's so important here in Korea, that it's actually a taboo for swearing! I can't really think of ANY taboos in English swearing, though there are some topics, for example, cannibalism, that don't come up very often, simply because most cursers aren't creative enough -- but if a good creative curser tossed a reference in, nobody'd say "Whoa, man. That's too far." People would probably just shake their heads in wonder, impressed that Joe Crass managed to pull such a creative curse out of the air.
Swearing is a funny thing. Swear words are the most onomatopoeic words in almost every language -- that is, of all classes of language, they're the words whose sounds most perfectly match their meanings (other than real onomato- poeias, like "bang, crash, splat, boom"), and frankly, they're delightfully fun to say -- just forming the words with your mouth can be a good catharsis, because a good swear requires your whole face to say it. The Korean "worst word" (18 -- you know the one) requires your whole face to say it properly, as does the English "worst word" (the F-word) as well as the new "worst English word"s -- the ugliest racial slurs.
And you know, listening to a really good curser, is a kind of poetry of its own -- I'm told Trainspotting is a great movie to hear some good cursing, though I have to watch it again. My own two favourites are "South Park, Bigger, Longer, and Uncut" -- the movie that first gave me an appreciation for a good, colourful, blue streak -- and "Full Metal Jacket" -- the first half of which might never be topped, which goes so far over the top it's absolutely hilarious.
(uhh. . . swearing warning)
(Any others I'm missing?)