both. Older people refrain from using it, but for young people it's just an innocent filler word. We don't beep such words out on TV/Radio, and they can be said in primetime by guests without problems.
And therefore it's easy for Danes when visiting USA/UK to say it without realizing that Americans/English people considers it rude.
It kind of shocked me when I came back to Denmark. Then it just amused me. It's funniest when people write it as "fåhk", which I'm seeing more and more.
It is also probably the reason why DHH uses it so liberally in keynotes etc. It might have happened unwittingly of course he has made it his trademark now.
25% of the content of my favorite (only?) Danish startup podcasts http://thorborg.tv/ consists of this word.
And therefore it's easy for Danes when visiting USA/UK to say it without realizing that Americans/English people considers it rude.