I just left Mr. Merrill's office and he says that he doesn't want to 'jump to conclusions', but I agree with you that what happened is pretty obvious. If it were up to me, we'd be over there cleaning it up now, but he said to wait so my hands are tied until that changes. But I take full responsibility and I'll do what I can do see that this doesn't happen again.
That said, don't call them delinquents. It was an inconsiderate joke, but it wasn't a crime. You shouldn't blow it out of proportion.