I wouldnt say i was a grass, although when i got (badly) beaten up, i told my parents who did it, they informed the police and everyone called me a grass. I thought that was unfair.
No .. I was always outside the headmistresses door for some misdeamour or other .But let on about my schoolmates...no way . I was very good at dodging the blackboard rubber .Which is why I still have friends whom I have kept in touch with for over forty years and we still laugh about the the goody goodies when we meet up every year.
People who cannot keep their mouths shut about silly schoolgirl pranks usually turn out to be the ones who are the fools .