Call me sick,but I would most definitley find a joke about any of my family members deaths humorous(as long as it was funny).A tasteless crack such as "your moms dead and rotting right now" would be obviously stupid,but something halfway funny such as "your dead mother just called me,she said I was fu*kin hot!" would be just fine.
Azrael was right when he said humour is the way humans(some)deal with tradgety and loss...

Later! \m/