That was pretty clever though maybe she could have chosen a better message. I am guessing she did not come up with the idea on her own. And I am guessing that the yearbook sponsor is not educated enough to recognize a coded message and thus missed the word ASS. I doubt there are more than ten people in the graduating class who would have figured out the message.
And who will see it 10 years from now. Good grief. If no figure it out till it was in the yearbook then forget about it. These administrators are Nitrogen, Uranium,Thallium, Sulfur. NUTLS.