The school I work at decided to have a lockdown drill without giving the teachers a heads up, so when they came on the loudspeakers and said, "Teachers, enter lockdown immidiately" I thought it was real. I barricaded the door, passed out heavy things to throw if they got in anyways, and briefed them on possible evacuation routes if we got information that the danger was on the other side of campus. A few minutes of trying to shush my riled up students later, they came on the announcements to tell us "The lockdown has ended." They never gave us an official statement that it was a drill. I learned later by word of mouth. One of my students snapped me building a barricade and I'm now Snapchat famous among the student body.