When is it time?

When you're invited to someone's house for a party, when is it time for you to leave? When do you know you have overstayed your welcome? And is there such a thing as overstaying your welcome? What if the host kept insisting that you stay longer, does that mean you have to do as requested or does that mean the host was just being polite? All these questions raced through my head when we were invited to an early Christmas lunch that lasted into dinner time and by the time we left it was nearly bedtime!