Their secrecy comes from using PHP, they don't want their families and friends to know
Friend: So where do you work?
Employee: Pornhub! I work on machine learning algorithms that automatically tag millions of porn videos for specific fetishes!
Friend: OK... What language do you program in?
Employee: Erm, well, uh, nevermind, it's a special hypertext preprocessor language, you've probably never heard of it.