I hope I was never that horrible (I'll confess to not being great at times), but I do remember enough to know that as a teen the temptation to side with the bullies over the bullied was strong. I was on the victim side of that, too. Social media definitely provides additional opportunities for the breadth and depth of such activities.
If I was a parent, the one message I would hope I would manage to communicate is:
Be excellent to each other.