What is the cause of a rebel?

Last week 6 students at a Cypriot school in Limassol, during their Religious Education lesson, got up from their seats, pulled down their pants and took out their male genitalia and showed them to the teacher. They then continued to take photos of the spectacle, with their male teacher in the background. As a result of this behaviour, the 6 boys were expelled from the school and were denied access to any other Lyceum of the town of Limassol. Currently, 2 of the students are attending school outside the region of Limassol, while the fate of the other 4 is unknown. The religious education teacher while distraught by the event, has resigned from his position as a teacher. I agree that this behaviour was unacceptable and disgusting, but what made the boys do so? What drove them to want to pull out their penises and show them to their teacher? Frankly, these 6 juveniles must have some suppressed anger in them, or a need to rebel against authority so as to seem "cool" in front of their peers, while over all they don't realise they have ruined a man's life and probably their own. This "Being Bad" persona must have a deeper meaning than just being a rebel without a cause...