Dark humour is a genre of humour which is characterized by its dark or morbid content used to pass issues that are normally sensitive or taboo. The current study is an attempt to investigate dark humour, as a politeness strategy in 4 posts that are in English and by Western speakers, the first two are extracted from Facebook and are against Muslims, the third from Twitter, and the fourth from Youtube and are in defense of Muslims. The study, while adopting Brown and Levinsons politeness theory (1987), aims at finding out the role played by dark humour in utterances that are for or against Muslims and how far such roles differ accordingly. It is hypothesized that dark humour can be an aggravation or a mitigation strategy depending on the speakers/writers stand in relation to Muslims. In conclusion, dark humor can be used to aggravate or mitigate the face threatening act towards Muslims when the utterance is meant to be against Muslims, and it can only aggravate the face threatening act against those who attack Muslims when the utterance is meant to be in their defense.