For teenagers (or anyone else) that has absolutely nothing to do with themselves for an evening, an afternoon, or for days at a time, a safe and healthy way to spend your time is to volunteer.
The local hospital or nursing home could always use a cheerful, pleasant person to assit with basic things and the patients/residents look foward to someone nice and pleasant.
Is it an amusement park? A Pizza shop? No. Is it a safe, clean environment? Yes. Try it.