Bong Hits for Jesus

This week in American Studies, we've been discussing the supreme court case Morse v. Frederick, or more commonly known as "Bong Hits for Jesus".
In my opinion, I think that the boy who hung the banner that read "Bong hits for Jesus" was being a tad irrational. Usually, I lean pretty far to the left on preserving civil liberties, but I believe the actions of this kid, although hilarious, were stupid and unnecesary. I have a lot of sympathy for the principal; I mean, if my school area were on television and someone hung up a banner with that slogan, I would be sprinting to tear it down out of pure embarrassment.
On a different note, I'm not sure if this is a free speech issue. Is it against school/community rules to hang up banners or signs without the consent of an official? Because if so, the kid deserved to be punished. If the banner were in the school, I would have said that he should have gotten in trouble; but since the banner was in the community, just outside of the school, I'm not so sure. I believe that the kid should have gotten in trouble, but I don't think that he should have gotten suspended. Also, if you don't need consent for hanging banners in the community, the boy should not have gotten in trouble.