The Goth Scout Opera continues

This gag is built on a negative principal, that the doctors who usually make patients sicker in fact do their job and therefore incur the wrath of the Angel of Death, who has just wasted an entire half an hour listening to Hannelore sing about dying. To find out the origin of the phrase "so sue me" and its meaning you can go here: http://www.phrases.org.uk/meanings/so-sue-me.html
It generally means, "I did something wrong and there's nothing you can do to make it better." I thought it was funny that a chorus of doctors would sing "So sue me".