Everyone stare at the teacher for about 15-30 minutes, and do nothing else, then when she seems relativity annoyed everyone needs to start reciting "Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn" repeat this in unison twice, then all stand up, and walk towards her chanting "Cthulhu fhtagn" Stop about 2 feet from her and stare for 10 seconds, everyone lifts there hands up in the air and points at her, and quotes Abdul Alhazred. "That is not dead which can eternal lie./ And with strange aeons even death may die." Precede to add another things from the cuthulu mythos and stare at her, possibly a necornomicon should be brought in and someone should say "Yog-Sogoth demands your soul" or something along these lines.
I like posts like this, because well my idea may be ridiculous, and as many pepole have pointed out you should be able to come up with something decent rather quickly, and if not maybe you should be studying, it is still open ended enough to present the ridiculous things i have had floating around in my head.
Also you should reenact one of Charles Dexter Ward's experiments on her, that'll show her.
I am not responsible if you use any of my ideas, however the staring and chanting would freak her out enough to leave you alone or get you all detentions, probably the latter.