UPDATED - clip replaced.
The following video was posted on Facebook originally, and is beginning to cause quite a stir.
Writes the poster on Facebook, Merlsification: "The larger kid on the right, is my son's friend Casey - thankfully they don't go to the same school. Poor Casey has been bullied his whole high school life, and this is what happens when he snaps!! But guess who was suspended in this scenario - Casey!!"
The bullied kid who fought back already has his own Facebook support page.
Watch, AFTER THE JUMP...