This nickname is used because of the similarity in sound to Kostas, a Greek short form of Konstantinos or Constantine. (The "k" (or kappa in the Greek alphabet), would be "unaspirated," that is, without the puff of breath following an initial k or c in English (the k of "kin" or the c of "cot" as opposed to those of "skin" or "Scot," respectively), and thus sound something like a hard "g.")