Or you could just grow up, go without your social diarrhea for a few hours, get yourself some good grades and then have a great job that allows you to use Facebook because you're so high up the corporate ladder! No? I didn't think so.
Your best bet is to use a proxy or your smartphone. Believe me when I say this... your school technicians are smarter than you. If they don't want you on facebook you're not getting on it. It's that simple - sorry!
Saying that I did bypass my schools security back in the day for my peers at a rate of 50p per session; it was the easiest 'business' I've ever run!