I used to get really angry if someone took a bit of my food back in my younger, fatty days. Now since I watch what I eat and how much, if I think I have too much I'll offer some to someone else. I won't mind sharing food with family and friends, but if some random stranger just came up to my plate and started taking some food, I would A) think they have lots of nerve, and B) tell them to get lost, although I doubt that would ever happen.