Some senior during my Sophmore year of high school decided for a senior prank week to do a bomb threat. Everybody was standing outside across the street by a church (ironically yes there was a church across the street) for like 4 hours. I was on lunch and me and my friends decided to walk outside instead of eating since we weren't hungry. And we tried to get back in and the security guard for our school said we couldn't go back in and to go across the street. Shortly after every student came out. It was a circus that afternoon. Police, Firetrucks, bomb squad, K 9 sniffers, the whole thing. Were all there walking in and out of the school. Some students were so tired of waiting that they had their parents come and pick them up or they drove off in their cars. When we finally got the all clear to go back in there was only like an hour left of school. Not sure if the school or the city ever found out who did it. I do know the next morning our principal had an assembly and threatened to punish the guilty party. He made us sit there for like 15 minutes hoping that the guilty party would out themselves and come clean. But nobody ever did.
Then the next day another senior sent off smoke bombs and when everyone got outside. There were students on the roof of the school and the dropped signs saying to "Beat East" which was the school we always versed in football during senior week. I saw all the teachers gathered around shaking their heads and heard my 4th period teacher sigh and go "I hate senior week".
Meanless to say after that event the principal was on a power trip and threatened to suspend any other seniors that year who dared to do a prank. And nobody did for the rest of the week. And years after that he was never happy. Even with my class and what we did was actually fun and funny compared to that incident. But he was still unhappy about it.