@dotnetN00b: That is definitely very American English, and (as a Brit) I would feel awkward addressing anyone I didn't know as "sir" or "ma'am" or indeed anything. I don't think there are particularly natural-sounding words in British English, and I'd just go for "erm, excuse me" or words of the sort. So maybe it's not too strange to do so in Japanese either. :)

Can I ask why this answer was downvoted? Is the information inaccurate?

@TsuyoshiIto: (1) It was relevant up until the point at which it was explained. After Matt's explanation of the word "idiomatic" (i.e. before comments from you, sawa, Dave and istrasci), the question became clear, your thoughts on the matter became irrelevant, and the subsequent discussion of an English word between (I think) two Japanese speakers, while both failed to produce an answer to the original question for almost a full day, became rude. (2) Okay, though even half-finished thoughts from a native speaker are better than nothing. I appreciate your eventual answer, anyway.

@TsuyoshiIto: (1) This meaning of "idiomatic" was pointed out long before you stopped debating it. This in itself isn't bad, but the problem is the next point: (2) This is entirely reasonable, of course, but please consider how it looks to those who ask questions for you to nitpick and show no signs of writing an answer. If you're writing an answer and it's taking you a while, but you want to discuss issues irrelevant to the original question in the meantime, then that's fine, but in my opinion it's just sensible to point out that you're writing an answer, so as not to seem rude.

I find everyone's bickering and nitpicking quite rude. It doesn't matter what you think "idiomatic" means or doesn't mean here. Someone who knows the answer, please tell the original poster (and me, and anyone else who might want to know) what the words おじいさん and おばあさん mean, literally and figuratively, and what connotations these words might have, and how natural they are in the context. Any answer along these lines I'm sure will be sufficient. (And please stop attacking people for not knowing how to ask their questions - isn't that how everyone starts out?!)

しゃべる, on the other hand, means "to chat".

Incidentally, you'll notice that this has been tagged with "politeness", which may be related to the comment I made in brackets above.

@DaveMG: Makes sense, and I somewhat agree with you. Perhaps I've accidentally swept under the rug what Paul said. I didn't even understand the title of this post correctly when I first saw it - not only is this use of "cool" to mean "acceptable" very modern and non-standard English, it's also very specific to America (and those who watch too much American TV ;)). It's unreasonable to assume words like "cool" and "かっこいい" (which aren't really that similar anyway, outside of a few contexts!) have developed in the same way, I think. I wrote my comment with this in mind, but failed to voice it. :)

@sawa: Well, "grandpa" and "grandma" are very definitely not literal terms - they are practically young people's slang in this context. I think Andrew is asking whether the Japanese terms are anything more than that. (By the way, the English terms - when not used by grandchildren to grandparents, of course - are intended to be rather disrespectful. I get the impression that this is not the case with the Japanese terms.)

I hope this doesn't seem like obvious and patronising advice, but I think the correct thing to do if you're not sure is to assume idioms, slang and alternative meanings don't translate and rephrase your sentence unambiguously. It's for this reason that, when learning a word, I will always look up examples of where Japanese people have used it and then assume (until told otherwise) that those are the only meanings allowed. In short, never learn a word out of context. :)

@Tsuyoshi: then perhaps you can explain it. That would be useful.

@languagehacker: I don't think you should think of the informal language as being rude in its own right, more as a symptom of the rudeness. Perhaps fefe's answer is closest to the truth. The pirate is a very rough character - when he asked for the wine, the other guy didn't apologise, but instead told him something to the tune of "nah mate, none left" (or translate this into your favourite 'rough' English dialect) and smirked. If I got treated like that I think I'd be annoyed too! The informal Japanese is kind of a way of saying "I know how I'm acting and I don't care, I can do what I like".

The reading is different, but I am reminded also of 上手 / 下手.

@DaveMG: Native speakers know what is common and what is uncommon, and that's all that was asked. I have no way of checking the validity of others' information. This is not physics: the only way I can check anything is to ask someone more experienced. Besides, I'm not suggesting you should trust, say, a grammatical explanation from a native speaker to be complete or even correct. I'm saying it's wrong of you to berate this person for giving proof that they knew the answer to this question. Appealing to authority, while undesirable, is often the only thing you can do.

@DaveMG: This was not a comment about why or how. It was a simple statement of what was most common in spoken Japanese. Don't forget that most of the community are not native speakers, and the questioner is not a native speaker - the correct information is not determined by democracy, and native Japanese speakers have pretty much absolute authority on the topic of what is said in their language.

@DaveMG: I don't understand. The above poster was confirming that their answer was correct, and that they had experience to back it up. It is not important that a poster thinks that (s)he is correct, it is important that others know whether (s)he is correct or not. Foreign cultures are a subject about which there is a lot of widely available crap written by amateurs who once read a Wikipedia article and misinterpreted the subtleties, and I appreciate those with experience (or those with no experience) pointing themselves out.