I spend some time in a chatroom elsewhere and a person came in, talked a bit and then started being fairly vulgar, but with no provocation, and had been otherwise amiable and carried on a normal conversation about the site's topic for at least ten minutes prior to this.
The other few people in there were understandably confused and irritated and though only one responded in kind, the others asked or told him to stop, and he responded it was a clinical medical condition he had.
I can't recall the name but I'd recognize it if I saw it again. I found it online and it is a legitimate diagnosis, but online, there is no way to tell if someone has it, or if he was simply trolling.
He wasn't attacking anyone, just using crude, offensive language, in a hypothetical sense, so it is possible he was being honest, but... Even assuming he was telling the truth, what an awful affliction (I've never seen him in there again), and surely there is medication even for that, and why wasn't he on it?
See, chat rooms (and other online communities) seem to have a different social dynamic. I think it's because you don't really know who the other person is. Anyone could be anyone, it doesn't matter who you say you are. It makes me, for one, believe that the normal social rules don't apply.
I wouldn't be shocked to find out that the person you are referring to was a teenager, probably male. I remember being 14 or 15 and thinking that dropping that f-bomb was the highest compliment that you could pay something. When I was that age it was used almost purely for emphasis. As in: "That song rocks my f***** socks off everytime I hear it."
Bad language is distasteful for me. I grew up without hearing anyone in my family saying anything unkind so I guess when I do hear it I'm just thinking the person is so rude for speaking like that. Someone that is very intelligent can use choice words to express them self without having to sound like ghetto trash.