Leo Rosten, in his classic (and funny) book, The Joys of Yiddish (McGraw-Hill 1968), says the word schmuck is defined first as an obscene reference to the penis: "Never use schmuck lightly, or in the presence of women and children. Indeed, it was uneasiness about schmuck that led to the truncated euphemism shmo....", wrote Rosten. Ibid. p. 361 ...