“I did it by hijacking every networked display in every school to broadcast "Never Gonna Give You Up" in perfect synchronization.”
A district with 11,000 students had security cameras on its network with no password at all. Students scanned half of a /8 before anyone noticed, and the response was a polite request to stop. The prank came with a 26-page pentest report. The district got a free security audit from a teenager, and the teenager got lucky it didn’t press charges.