Technically not any stuff. I believe the current morale penalties are rewarded for killing zombie children, your mother, innocent npcs, and nothing else. These already have a negative cap to them. I believe children can give up to -100 morale.
However, I believe the moral penalties given for npcs is insanely long-lived. Which, makes this even better in how disturbing it is.
Jessica Lynch, high school student and future serial killer, is having a typical bad day. She’s out of smokes, it’s raining, she’s hungry, hung over, and tired. She’s receiving pretty hefty penalties for all this. However, none of that matters because she’s still high as a kite after shanking and butchering that random hobo.
Seriously, the idea of a Jessica Lynch being out there is terrifying to people when society is functioning. Knowing that a survivor might be one of these? Mind shattering.