I’m an old guy, so my senior year of high school was when our school got class computers that connected to the internet (dial-up).
The installation happened over the winter break, and when we got back, suddenly our social studies teacher began showing videos in class. Like every single day. For a while, we thought he was just burned out until we noticed that during every video he had his computer monitor turned awkwardly so that no one at the back of the class could see it. After a couple of months, the administration looked through the records for internet use and noticed he spent a lot more time online than everyone else. When they dug deeper to see what he was doing, they learned he was spending entire days surfing porn sites during class. He was swiftly and unceremoniously replaced in the middle of the term.