Founded South of Boston, the term refers to a pain in the neck squared. The idiotneck is the epitome of part-donkey, part-unscratchable itch that festers in our neurological systems and can usually only be removed with surgical procedures such as lobotomy or a blindfolded bris.
At the sleepover, he was acting like such an idiotneck that they were forced to power up the treadmill he was sleeping on and it splattered him all across the Night Rider pinball machine.
A takeoff on idiolect (1948), which means, "the language or speech pattern of an idiot at a particular period of life", specifically, "the language or speech pattern of one individual idiot at a particular period of life".
Though his idiotlect as a teenager was more pronounced, at 36, it is still clearly discernible. Idiolect could be called "idiolex" to emphasize "lexicon" (a person's vocabulary).