A downvote, I knew it.

I'm voting to close this question as off-topic because this is a question about sociology, not English.

@HotLicks Interesting, so I take it that the expression has become a highly charged expression. Did you actually read the post, and the questions listed at the end?

@HotLicks I can kind of see how “is this an emotionally charged term?” can be construed as sociological more than linguistic; but “has this term caught on in the UK?”, “how offensive is this term?”, and “what are alternatives to this term?” are all purely language questions and perfectly on topic here.

@Mari-LouA I get the sense from your comments on the appearance of some of these people apparently plagued by RBF that you perceive that looks are an important factor. For what it's worth, I've never thought of it like that: you can have RBF whether you're stunning or Quasimodo. It's all about your neutral, relaxed facial expression being one that makes you look like you're angry or unapproachable—i.e., signalling (usually incorrectly) something about a person’s attitude more than their looks.

@Mari-LouA The video of Madeline Mann definitely has no RBF in it, but it doesn't have any RF in it all: she's smiling (presumably deliberately) rather than resting her face in a neutral expression, so it's impossible to judge whether she really does have RBF or not. Olga definitely looks pretty sour and RBF-y to me in the picture of her as a child (though perhaps that was an actual, angry face). The adult picture looks too posed and deliberate to be a good indicator either way. I don't think Conan’s the best example either, actually—he looks more sad than sour to me, like he's about to cry.

Sorry, can't help. Never heard of it before.

Know Your Meme has an article. Puts the origin at 2009 or before, although it only gained popularity in 2013.

I think it's pretty offensive for a number of reasons, primarily because it pre-judges a person on their (unalterable) appearance, however, I laughed the first time I heard it. Conan, though, does not have an RBF. That's not how he usually looks. And I've never heard it applied to a man, but then again, I don't hear it too often.

Never heard of it. Yes, 'bitch' means a female dog, but used of a woman it's pretty insulting here in the UK too. I happen to have a mouth whose corners turn down in repose, like the man in the picture, so I may be perceived as glum when I'm not.

1) yes, it's emotionally charged, but the emotion is more humor with a back-handed compliment ('you look mean but are probably nice inside'). It isn't offensive beyond the 'you look mean' part and is in fact more understanding. 2) no idea about UK. 3) You did so much research already I'm surprised it's possible to squeeze out more. How did it originate? Somebody just made it up.

@Mitch I never asked "how", I asked "when". The anonymous comment, which I posted, sounded quite "mean" to my ears, maybe I should say who the target was?

Re How vs when, yes, I answered a different question because it seems to have been answered as well as it can already (and that 'somebody just made it up' could mean that it is impossible to say exactly when it became a 'thing' or by whom).

Re 'mean' anonymous comment, did you mean the post by 'justposting' from utopia? If so, RBF was used in a mean context but is only offensive to the extent that it is vulgar (by use of 'bitch') and the implication that they on't look happy. To accost someone and say 'you have an RBF' is only offensive if you are upset that they think you are not smiling enough.

@Mari-LouA a word used in a sentence in a malicious context doesn't make that word malicious. there are many non-malicious uses of RBF that aren't offensive. RBF tends to be used about oneself though. Re 'penalize/dismiss' - why so cranky? I thought being thorough was good.

I thought so too, so why the dismissive comment: How did it originate? Somebody just made it up. When I didn't ask "how". Was that comment particularly helpful? Constructive? And, my edit today proved that there is still something to be squeezed. I waited a fair bit before updating it. Not 100% convinced the bounty will actually shift anyone. Besides, I'm past caring, too busy with RL :)

Sorry but I wholly agree with Hot Licks… (please note the sorrow is for the content, nothing to do with Hot Licks personally!) The origin of the phrase is blindingly obvious. Personally, I've never head of it though I've been speaking and reading UK English for 60 years. Of course it's offensive. A useful question might be 'how could this not be considered offensive?' If anyone doubts any of that, other than the UK familiarity, please try replacing 'RBF' with the earlier 'bitch'. Now, what's the difference, please?

It would be interesting to see, when, under what circumstances and about whom it was first said. As it's presumably a recent phrase these would have a bearing on the implications when it's seen. I think the question is a good one.

To address one sub-question, grumpy resting face (Google search for examples) is probably your best bet for an accepted, descriptive but much less offensive equivalent

@ChrisH - curiously, the expression is cited in common dictionaries and none of them refers to is as offensive : 1) en.oxforddictionaries.com/definition/resting_bitch_face - 2) macmillandictionary.com/dictionary/british/resting-bitch-fac‌​e

@Josh, that's fair enough, but it must be close to the line. Too close for me to use it

@RobbieGoodwin - why do you thinink is offensive? The dictionaries entries (see my comment above) don't define "resting bitch face" as offensive but just as informal or humorous. Could that be a generational issue?

@Josh I can understand how, in the US, it is construed as offensive to the subject being referred to, regardless of the online definitions. It's basically saying that someone has a face that, in it's normal, unedited state, makes them look like a bitch. I understand how one might find that offensive 100% of the time lol.

@Hank - it is not only about a few online definitions, the expression appears to have a more common "neutral" usage than one might expect. But I understand that the term bitch is a strong one.... edition.cnn.com/2016/02/03/health/… - washingtonpost.com/news/arts-and-entertainment/wp/2016/02/02‌​/… - noldusconsulting.com/blog/…

@Mari-LouA - nobody dares to tread on a "bitchy" territory - :)

@Josh That last post is a good one (only one i read fully). It relates contempt to RBF, which, in my opinion, would contribute to it's negative connotation. It summarizes that RBF implies the person is showing "anger and sadness directed at those deemed below you." I'd say that carries a negative usage.

@Mari-LouA I also this the last page Josh posted a couple comments up will provide you with a lot of information.

Josh, Guys, Common Dictionaries: test for offensiveness by using the expression directly to and about any of the dictionary staff, particularly female staff.

I am soo fed up of seeing comments. I will ask the mods to delete each and every one very soon. The question is about language, and meaning, and connotations, and slang, and neologisms, and American English vs British English, and usage, and offensive language vs self-mockery. Damnit. It's not being taken seriously because, evidently, men don't use it.

This question shows a lot of research effort and that should be enough to get my upvote. In addition, it's also clear, well-written and perfectly on topic. I don't have an answer but I'm looking forward to seeing a good one here.

Native American speaker here. I heard it the first time a few days ago in another question here. It is an incredibly offensive term and I would think less of anyone who used it about anyone.