A foray into an oddity of word-making. Outside the province of jokelore, this type of abbreviation appears to have escaped notice in the literature on word-formation, perhaps because its productivity, besides being quite low, can best be seen in the most informal – and therefore supposedly ‘abnormal’ and ‘disreputable’ – levels of discourse. Of course, one does not have to be a genius to be aware that most knock-knock words (KKWs) stand as much chance of surviving as a snowball in hell. However, they are to be cherished for the unique insight they provide into language play and linguistic creativity at large. In what follows, I will describe the structural and semantic features of these words and present a glossary with a sprinkling of specimens gathered from a variety of sources.