I cannot think of any word my friends or me would find offensive which is why I have to take care not to say the wrong things when in other countries. I was raised in the Netherlands in schools where we had plenty of religious discourse and we all (my friend group) became atheist, so anything using the lord's name in vain wouldn't bother me at all; it doesn't even register most of the time. And then most of our parents didn't want to shield us much from the big-bad-world, so swearing US humor and UK humor were normal as well. I really didn't know until I met my aunt from Canada for the first time when I was 9 or 10 that 'fuck' is not normal in some circles. Note this was the early 80s; no internet, very limited communication besides few BBS's + magazines + tv + local (Dutch, no foreigners) events. I don't see anything wrong with it; some words are just 'stop words' but to respect other people's feelings I try not to use anything that I know is considered 'bad' in those circles.

It always amazes me that rich/educated people swear a lot and poor/uneducated people swear a lot but in between (middle-class) everyone is ultra polite. At least that is what I found from the limited (as one person of course experiences cannot be very broad) set of meetings in NL/UK/US.