Cultures around the world have restrictions or prohibitions on when sex is allowed which turn out to be quite amazing in their diversity.

This is a fascinating section on the wide world of sex taboos from the Encyclopedia of Sex and Gender:

In some societies, sexual activity is prohibited during certain times of day. The Cuna of Panama approve of sexual relations only at night in accordance with the laws of God. The Semang of Malaysia believe that sex during the day will cause thunderstorms and deadly lightening, leading to drowning of not only the offending couple but also of other innocent people. And the West African Bambara believe that a couple who engage in sex during the day will have an albino child. Sometimes, sex is prohibited in certain places. The Mende of West Africa forbid sexual intercourse in the bush, while the Semang condemn sex with camp boundaries for fear that the supernatural will become angry. Among the Bambara, engaging in sexual relations out of doors will lead to the failure of crops. Sex taboos can also apply to certain activities. Often, sex prohibitions are associated with war or economic pursuit. The Ganda of Uganda forbid sexual intercourse the night before battle if the fighting is likely to be protracted. The Lepcha prohibit sex for three months after a bear trap has been set. If the taboo is broken, no animals will be caught. The Cuna of Panama outlaw sexual intercourse during a turtle hunt, the Yapese of Oceania prohibit sex during a fishing excursion, and among the Ganda of Uganda sex is forbidden while the wood for making canoes is being processed. Ganda women may not engage in sexual intercourse while they are mourning the dead and Kwoma men are prohibited from engaging in sexual activity after a cult ceremony has been held. The Jivaro of Ecuador refrain from engaging in sex after someone has died, after planting narcotics, when preparing a feast or after an enemy has been killed.

Of course, while these may seem exotic, our own social practices regarding sex probably seem equally as unusual to outsiders.

Imagine Jivaro anthropologists, watching Nicki Minaj videos, slapping themselves, shouting “you won’t believe what the people of North America have to do to have sex!”

Link to section from the Encyclopedia of Sex and Gender.