In what cultures is sex a not-private affair?

It could be a general sentiment or for certain occasions. I have heard of sex of newly-weds in front of their grandparents (in an African culture, unfortunately I'm not sure which), public ceremonies in various cultures that involve sex (or sometimes rape), different standards in terms of household members being able to *hear*, etc. I'm curious to learn more about that, particularly in terms of how people think/feel about sex as not an intimate act.