A convenient contraction of the two
words balls and itch. The male genitalia is one of the most optimum places on the body for bacteria, parisites, and fungi to flourish. Some of these things cause the tesitcles to itch. When this occurs, it saves time to simply say "Ballzitch" and
scratch your testes until alleviated rather than have your
friends ask, "Were you just playing with yourself?"