Taboo
See Taboo
Taboos are the way that culture enforces social norms of behavior that are not applicable to the legal system. The most common taboos throughout history revolve around our sexual morality, but they also include things like not farting in mixed company and extreme behaviors like cannibalism.
The Need for Modern Taboos
As belief and participation in religion declines, so has the ability to enforce taboos and other cultural norms. In many cases this is a good thing. The sexual revolution freed us from many unnecessarily and debilitating taboos, allowing people who enjoy sex outside of procreation (everyone) to openly be themselves. However, there are some traditional taboos that have been lost that we are starting to miss.