How to traumatise a pedo?

There is a man (40 somth) that works in the cafetaria of my school.

He asked a lot of girls to come over at their place, or to come to his place. Always flirting with the 'pretty' ones, while being a dick to guys and other "less attractive" girls. Ofcourse the school ain't gonna do shit, so I need to do something so outrageous that he won't talk to me anymore. A lot of girls are scared to speak up (understandable), but I don't have a filter, so what can I say or do to traumatise him?

Thanks in advance :) OP