This video captures the stomach-churning moment a physics teacher swings an axe into his co-worker's genitals - in a disastrously misjudged class experiment.
The nauseating footage was captured on a camera phone at a school in Portland, Oregon, and shows the well-built man lecturing a crowd of students before excitedly asking 'everybody ready?'.
The teacher then orders the class to give him a count as he hoists the axe up over his head and swings it directly into the unlucky fellow-teacher's crotch - causing him to squirm violently on the floor.
The idea of the experiment appears to be to crack open a cinder block that is balancing on the chest of one of his co-workers using the blunt end of the axe.