Many foreigners consider the Dutch language shocking, particularly commonly used words for "taboo" topics. For example: one of the most common exclamations (for surprise, shock, dismay, etc.) is "kut!", which literally translates to "cunt". The word is not considered very shocking in Dutch - somewhat vulgar at most - and can be used by almost everyone. You could say "Ik voel me kut" (lit. "I feel cunt(y)") for "I don't feel good", or "Het is kutweer" (lit. "It's cunt(y) weather") when it's raining. When someone bad happens, instead of "I'm sorry to hear that", one could say "That's so cunt for you," without sounding disrespectful. I would go so far as to say it's not even as vulgar as the phrases "I feel like shit" or "The weather is shitty" would be in English. It's not a word you'd use around small children, but really hardly considered a "bad" word in normal conversation.
I think the underlying reason for this has two aspects: firstly, describing intimate body parts is considered much less of a taboo in Dutch than in some languages. And secondly, the Dutch just don't use many euphemisms. For example: when someone has to use the bathroom, they may say "I have to go to the toilet", or "I have to pee" - plain and simple. We don't have words such as "restroom", "washroom", or "lavatory". The most common word used besides "toilet" is simply "W.C.". English phrases such as "bowel movement" or "no. 2" are only very seldom used in Dutch; they'd be considered too vague and unnecessarily confusing. (I've, actually, only heard equivalents being used in religious families.) Similarly, the Dutch language never uses asterisks or bleeps to censor out words or parts of words (such as "f***", "sh*t", or "The F-word"), except when directly quoting from an English-language source.
When we do use metonymy in Dutch, it's not to hide what we really mean, but actually to emphasize it. By using words and phrases that are more vulgar than what would commonly be said, a dissonance is created - a regular phrase with one vulgar word - which has a humorous result. By saying something in a humorous way, the tension is lifted. For example, when describing a taboo part of the body such as the genitals, an English speaker might refer to their "pubic area". A Dutch speaker is more likely to simply talk about his "crotch" ("kruis"). Although the word is more vulgar than medical terms or euphemisms, it is specific, sounds somewhat funny, and therefore can be used in most situations. (Somewhat similar, I suppose, to the speech pattern described in the "Sophisticated As Hell" article on TV Tropes.)
The same goes for most social taboos as well: in Dutch, a person is not "gay" but simply "homo", not "a person of color" but simply "black" (or, still quite commonly used, a "neger", which can be used neutrally). For people with Down's Syndrome, the word "mongooltje" ("little Mongol") may be considered an insult, but can be used neutrally or affectionately in most situations. The equivalents we have for "retard" ("idioot", "debiel") are very mild and can - for example - be said lovingly to children when they act silly, although they're also commonly used as insults. In its iconography, too, the Dutch culture sees no problem with blackface, traditional depictions of foreign clothes and facial structures, and emphasizing racial stereotypes: they're all considered good-natured caricatures, and people generally simply don't take offense.
The Dutch language does have its taboos: names of diseases, especially cancer, are considered too strong to use by most people. "Cancer!" is used as an exclamation, "Krijg de kanker" ("contract the cancer!") can be yelled at someone, and you could tell someone to "tief op met je kankerhoofd" (lit. "typhoid out of here with your cancer-head!" - in which "typhoid", in part, is used as a verb). These phrases are almost never used jokingly, and are considered the most serious insults the language has. (And yelling them at a police officer will get you arrested.)
I guess it's easy to see, considering these conventions, why the Dutch are considered crude and blunt by some. Whether being specific and using very few euphemisms makes a language more efficient would be up for debate.
I've been told that some Slavic languages (particularly Ukrainian) are comparable in "bluntless" to Dutch, and that Dutch is actually unique in its use of diseases as dirty words. I'm wondering how much of that is true. Also, what other languages commonly use words that would be considered taboo in English?