South Park tested the boundaries of hilarity last night by mocking US President Barack Obama's dead grandmother.

Madelyn Dunham passed away on Sunday only two days before her grandson made history as the first black President of the United States.

The episode - called About Last Night - suggests that Obama's grandmother faked her death and sees Obama, John McCain and Sarah Palin teaming up to steal the Hope Diamond from Washington's Smithsonian Natural History Museum.

Obama's grandmother is pictured phoning in a bomb threat to the museum as a distraction.

See stills from the episode below