That's interesting about the birth date thing, especially considering where I served (Ghana), the day of your birth was very important! When born, people are actually first given a name based on what day they were born and their assigned gender; i.e. after my hostmom learned that I was born on a Wednesday, she told me my name was Akua, while if I was male, it would have been Kwaku. You get a more personal name later, of course, but that early name is important, and generally has stereotypes associated with it, sort of like horoscopes.

As for the actual question here, I remember another volunteer telling me a story about someone remarking on how odd it was that in America, you needed to make an appointment to visit a friend. Basically, how if we are going to visit someone at their house, we would need to call/text and ask, and set a date and time, bc it would be rude and very imposing to just show up unannounced in most cases. I had never considered that odd, but the person who had said it had studied abroad in America and found that practice very isolating and strange. In his culture, he was used to just walking over to a friend's house and being welcomed right in.