Bad Manners and Brimstone

My father spent his teens in East Africa, and told me that among the Kikuyu people, if you're in your hut and see a stranger or a not-friend approaching you come out to greet them, get introduced, enquire after their health, blah blah. Which all seems very polite, but is actually keeping them out of your home until you have sized them up and decided if you want to invite them over your threshold. But if you see a relation or a real friend coming you carry on doing exactly what you were doing, and let them walk right into your hut and sit down before you put down your task and say hello. That shows your complete trust and acceptance of them.

Sort of like neighbors of old coming in through your back door with a quick knock versus a stranger or mere acquaintance coming to your homes front door and ringing the doorbell.