how about ...
Billy didn't get the memo about Funny Hat Day and spends the day making up excuses and stories as to why hes not wearing a funny hat. The tension escalates as Billy's increasingly bizarre stories cause his teachers to suspect Billy is planning a school bombing! As the police arrive, Billy runs and locks himself in the ART room full of kids. As everyone now thinks Billy is wearing a suicide bomb, there is much panic, the swat team, FBI, TV News are all surrounding the school waiting... Suddenly the doors swing open, A pack of students surrounds Billy, keeping him safe from the snipers bullet as one student explains the misunderstanding.. the pack of students parts revealing Billy in a very silly hat that the students made in the ART room...
Could end there on a happy note..
or..
The report of a rifle shot splits the afternoon, and Billy crumples to the ground..