For years I've watched as my children have had friends over and wouldn't you know it, they get into things they'd never get into before. Why? Because they didn't want to hurt their friends' feelings. However, if they knew they could tell their friends, "We don't do that here," and the friend was expecting to know that, then they could move on and have some fun.
From that day on each playdate at my house or at someone else's house began with, "Share your rules please." Such a simple phrase. Thank you C. for changing my life that day!