The “AIDS is not a bad person’s disease” scene from the Golden Girls.
I’ve been thinking a lot about how sitcoms seem to have lost that Norman Lear-pioneered style of seriously tackling really difficult, controversial issues with humor (Think All In the Family, Maude gets an abortion, etc.). I’d probably pinpoint the shift of that somewhere in between 1993 and 95 when Seinfeld overtook Roseanne in the ratings, and today’s current crop of sitcoms still largely reflects that shift.
Out of all the sitcoms currently on air Parks and Rec seems to be the best suited to make a return to that kind of subject matter. It might give the show a deeper level (and, on the cynical tip, sometimes controversy is good for ratings). I really do think everyone involved in the show has enough talent and grace to tackle issues a bit more controversial than gay penguins, and it does seem natural for a show rooted in politics.