competition: Best senior prank that your graduating class did

On the last day of school our senior year... my friend and I went to all 3 student parking lots, the teachers parking lot and the park across the street- hundreds and hundreds of cars. We took yellow window chalk and wrote "00" (for 2000) on every single car. Our school was 4,000+ students. (But, of course not everyone drives.) For weeks you could see the yellow "00"s on cars around town. We are still legends at that school when it comes to Senior Pranks.