Outdoor sex is sex work in public places such as parks, forests, public toilets, …
This is done by people with extreme sexual tendencies, not being forced by morality and social judgment.
For them, it is said that it is for pleasure and not to care about anything else.
So while most people have sex in the house, and keep it hidden as much as possible. Then the outdoor sex workers choose public places such as parks, supermarkets, libraries, … that are easy to be detected.
Suspense, fear but extremely excited, that’s what they went through. The more they try, the more they become addicted to this way of sex, and gradually they become a lot more courageous.