Model code of conduct
This one is recent. One model code of conduct that we follow with my daughter is that she should return to home before 8 pm. She is allowed to play downstairs with friends, but by 8 pm she should be back at home. A few min here or there is fine. Sometimes, we allow friends to come and play at home past 8, but usually that is the boundary. If it really extends then she has to listen to the lecture again.
Recently, a colleauge of mine had come down from USA and we (the team) went out for dinner. Needless to say that it got delayed and I got home almost by 11 pm. Wife told me the next morning that our kid was questioning as to why the code of conduct isn't applicable to me. She was asking "When papa comes late, why isn't he answerable to us? Why don't you scold him as well?" :-)