Don't worry guys, Mao is probably high on chemistry questions or something.
I personally dislike swearing but I think when students use it around each other in appropriate contexts it can serve to promote social rapport by highlighting their familarity of each other and comfort in general. But we must remember that the frequency of taboo language, 'tone' and attitude do bear relevance to this topic. Those factors of which suggest that he wasn't doing so out of the ordinary conversation.
The use filled in as an emphatic particle of high colloquialism, without the direct intention of damaging the hearer, but rather to signal his sarcastic seriousness on the issue.
Being offended in terms of the words isolated is warranted, but perhaps reconsider 'poor behaviour', as the usage wasn't necessarily of such nature. Maybe it is right that swearing on public forums is not a good thing, but there is a reason why the public swearing fine (as long as not obsessive) is so demised. Finally this is a jokes thread under the water cooler.
I think one of my points on last years EL exam was that swearing has become such social factor it has in many situations lost it's offensive effect, has benefits and that it has become part of the Australian identity in some people's eyes.
But for some it definitely is a sensitive issue, and I respect that. I just wanted to put out some thinking points if it is at all of any relevance.