'Everything human is pathetic. The ultimate source of humour itself is not joy, but sorrow. There is no humour in heaven.' - Mark Twain
Certain subjects are so taboo that they do not seem fit subject for humour. Jibes at minorities, sweeping generalisations and jokes on sensitive topics are deemed imprudent. This is true to some extent, as long as it is treated with irony. Bawdy jokes about gays, rape, race are a crass way to get laughs. It is what Germans call shaudenfraud. a way of laughing at other people's misfortunes. When Bernard Manning makes jokes about 'Pakis' we do not laugh because it is meant literally and conforms to stereotypes.
However, when you make a joke in the vein of Manning with undertones of irony, it becomes funny. You are not laughing at the victims of such tirades, you are laughing at the type of people who make those jokes in the first place.
For instance, the Peter Cook/Dudley Moore duo Derek & Clive, at its best, is thunderously funny. There are the kind of diatribes you might here at a pub in the heartlands of England. The word 'cunt' is used as punctuation. There are the kind of absurd claims drunken men make ('the worst job I ever had...'). We laugh when a man hits the deck and breaks his fucking neck, when Clive kills a thousand Jews in Golders Green after seeing Nazis on TV, why people don't 'label' things. One laughs, although one may not think one ought to. A laugh is largely involuntary. I still think that D & C is playing around with these type of stereotypes. It turns Bernard Manning on its head.
Likewise, in Mel Brooks' iconic film The Producers we get a musical skit called 'Springtime for Hitler.' Whilst some may think that the horrors of the Third Reich are too sensitive to even be lampooned, once more it is hilarious. A rag-tag of ideas, rather than a coherent ideology, it is revealed for all its silliness. Nazism is demeaned through laughter. Satire attacks fascism with laughter and consigns its subject to ignominy.
Pathos is also funny. Acute suffering - such as a terminal illness - is never funny. Though a more moderate type of pathos, such as falling over, is funny. The subject is clumsy and buffoonish; he elicits laughter. Laughing at this type of minor misfortune can be mean-spirited, but it diminishes staid moroseness. No-one wants to live in a portentous world where everything is taken at face value.