Have you ever had to discipline someone else's child?

I was reading this “Daily Fail” article today and it made me wonder where the line is when dealing with children that aren’t your own.

I’m not necessarily talking about physical punishment like the journalist in this article is but any kind of discipline. For example, if your child’s friend is staying with you and being badly behaved how would you deal with it? Do you just bide your time until they leave? Would you confront them about it? Tell their parents?

Has a child’s behaviour (and the way you dealt with it) ever come between the friendship of you and the parent of that child?

Or, maybe, like in this article, you have found yourself physically punishing a child that isn’t your own. What lead up to that moment and what was the outcome?

Where is the line for you?

I’m mainly curious about children that aren’t a member of your family rather than nieces, nephews, grandchildren etc but maybe you have an example of how discipline of a child has come between family members?