She should have been disciplined accordingly... Before that was published. With that said, you can't publish something and then come back and discipline. It just doesn't work that way! Without pulling too much school law into this thread, there is plenty of history that protects the school from censoring school sponsored publications such as newspapers or yearbooks. That little joke should have been caught during editing, not after the fact. Disciplined, yes. Published, no. Funny and creative, yes.
I'll bet this girl gets off scot free. The school will end up with H2S on their faces.