Out society which claims to be the most advanced and progressive one but has still few taboos.
Sleeping in public is a taboo, except in some circumstances such as at the beach, at the park in a sunny day, on travel devices (airplain, train, metro).
If you see a man sleeping in a park on a cold day you think he's homeless, thus if it is a warm and sunny days it could be someone resting.
Having sex in public is a taboo, however there are public places where people go just to watch other people mating (club privée, nightclubs,...)
Incest is a taboo, but sometimes there is a public story about a brother and a sister loving each other and having babies. For one story known, guess how many are left unkown. The law has no power to break a relationship, but can take away the children for their parents.
Walking naked is a taboo, but there are nudist beaches and even a nudist island in France (where people can go to the Post Office naked, for instance)