You don't quite have the question posed to the SCOTUS right. The issue is not whether "bong hits" is offensive, but whether educators have the right to censor speech during what ostensibly might be considered a school activity, if that speech is somehow deemed to be contrary to the "values" the school system is trying to teach.

The alignment of interests here, on the side of free speech, is really interesting. On top of the usual and expected civil libertarians, are organizations advocating on behalf of the religious right (really, the Christian right). They rightly fear that a win for the school system here could lead to even less freedom for students to speak in accordance with their faith during anything even remotely considered a school activity.

It's potentially a dangerous precedent, and given the oral arguments in the case, it's difficult to predict how the justices votes are going to line up. There is an "out," or at least an easy way for the court to split the baby. It's been proposed to them that they could hold that this did go too far, but that the school in this particular case is entitled to immunity since they did not know or have reason to know that what they did was clearly unconstitutional.

While I don't agree with that -- I believe it was under the circumstances clearly unconstitutional -- I'd prefer the Court take that path to one that would give educators even more power to censor and punish speech which expresses things they do not like.