It's being called the worst senior prank ever!
There was hay all over the floor, writing on the walls, and shaving cream on the lockers.
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It happened at the Sequoyah High School outside Knoxville, Tennessee. Students who took part say the situation quickly got out of hand.
Senior pranks are right of passage at many high schools. Often it's all in good fun.
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For example, seniors in Santa Barbara had a mariachi band trail their principal!
But this one in Tennessee may be the worst prank ever; so bad that 100 students will not walk at their graduation.
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