Not long after Columbine, 2 freshmen at my school got it into their heads to "test" the school by claiming to see some guy in a trenchcoat carrying a rifle go onto the roof through a service access door. What ended up happening was a 4 hour lockdown with the State Police, county sherrif and local PD doing a complete sweep of the school. The boys failed to maintain their story when grilled by the police and they were subsequently charged with false reporting and were expelled from school.