There are certain phrases that sound dangerous before anyone has even explained what they mean, and "the Devil's playground" is one of them. You hear it and immediately imagine flashing lights, questionable judgment, loud music, a bartender polishing a glass with the expression of a man who knows exactly how this evening is going to end, and at least one person saying, "Relax, I've done this before," shortly before demonstrating that they absolutely have not. It is a phrase that has been used to describe cities, bars, gambling halls, dance floors, amusement districts, beaches, back roads, nightclubs, websites, bedrooms, concert halls, casinos, and probably a few family reunions. Wherever people have gathered to do something exciting, forbidden, reckless, pleasurable, suspicious, expensive, embarrassing, or difficult to explain to their insurance company, someone has eventually stood nearby and declared the place spiritually questionable.
That is what makes the idea so interesting. The Devil's playground is not one location. It is not a town with a zip code, a fenced amusement park, or a poorly reviewed roadside attraction with a horned mascot and half-price admission on Tuesdays. It is a concept humans have carried with them for centuries. Every generation seems to create certain places, behaviors, technologies, and entertainments that respectable society is warned to avoid. Sometimes those warnings are sensible. Sometimes they are exaggerated. Sometimes they are based on genuine danger, and sometimes they are based on the terrifying discovery that younger people have begun enjoying themselves without completing the proper paperwork.