Or why is it some racist jokes are seemingly more acceptable than others. Jokes about Ozzies, Scots, Irish (here in NZ we English (Poms) are the butt of many jokes) are taken with a pinch of salt but even think about a joke about someone who isn't white and the PC brigade are up in arms?
Joan Rivers makes jokes about her husband who committed suicide and the audience always laugh and find it funny.
In an interview she said it was a release for her to mourn him.