A nasty mob would encircle the 'special' kid in our class, all mouthing silent words. Convinced that he had gone deaf, his agitation would increase rapidly. Five minutes was normally sufficient to produce one of the desired reactions - either he would burst into tears and attempt to escape the circle, or curl into a foetal ball whimpering softly.

At this point, we would all repeatedly scream "DEFFO!", which, rather than reassuring him that his hearing was fine, would instead induce a near cardiac arrest, and, on a good day, cause him to piss himself.