Report for dave evans
Approved stories2
Rejected stories (hidden) 4
SummaryShows promise

also consider :
random and impromptu slashing of the neck with metal combs, and surprise karate chops to the Adam's apple 10 seconds before a teacher enters the class.
This results in a complete inability to breathe, so you won't be able to answer the register. Which will obviously be your number one concern, what with not being able to breathe.

it may well be one of those 'school myths' but one of our chemistry teachers was alleged to have, as a hobby, wrapping small pieces of sodium (explosive when wet) in dry bread and feeding it to the seagulls which plagued our school.