If you can't recognize a retarded principal on that basis, you need to look again. What exactly goes downhill from "Don't Drink and Drive?"
"Look Both Ways before Crossing the street?"
"Just Say No to Drugs?"
Please. Profanity/Obscinity/etc is clear as day and this clearly has nothing objectionable and is pretty positive. The principal can go **** himself.
If the kid was wearing an anti bush shirt, youd all be patting the guy back.