K-pop. Cheating on exams. Even pornography.

North Korea on Tuesday warned against the disruptive influence it said smartphones could have on its isolated population, as the devices have begun to expose young people in particular to information and trends from the outside world.

In the hermetically sealed North, South Korean officials estimate that the number of mobile phones has risen to six million since 2008, when cellular phone service began as a joint venture between the Egyptian telecommunications firm Orascom and the North’s communication ministry. The country has a population of 25 million.
https://www.nytimes.com/2018/12/18/world/asia/north-korea-smartphones.html