Well, you can't really do much, being only a school janitor (Not that I'm making fun of them. It's just that, because you're a janitor, people will think you are low and stupid. Totally untrue, guys). You can, however, help people when they are being bullied on the spot by talking with the bully and reporting the incident to the principal. Maybe you could also try talking to the school guidance counselor about having a program about raising awareness for incidents like these.