1) a contagious inabilty to shut the fuck up, which easily spreads among the listeners.
Much like the white noise of teenage fans at a pop concert or the adult fans at a sports concert, except this disease has no rhyme or reason and then it seemingly stops for no particular reason. Usually there is one of two stragglers who try to keep the conversation going but the other peers no longer care.
Oh, here he comes again. If he starts his verbal gonorrhea again, lets just leave. I don't want to participate in his social experiment!