What went down:

Yesterday, I was in school in math class when this girl in my class started to beat one of the guys in my class. Why, probably he said something lame or something - but definitely nothing to warrant a thumping. My teacher came back in the room and they guy said he was hit. The teacher asked if anybody saw it - and i was the only one who said so - absolutely nothing was done.

TL;DR: Guy get hit, teacher wasn't around to see it, and doesn't care upon reliable testimony

THE ACTUAL QUESTION:

Is there any way a 17 year-old girl to deal with this situation (which she doesn't like) out in a RP fashion, or is it best to stay the heck out?