shyster: [19] Shyster ‘unscrupulous lawyer’ originated in the USA in the 1840s. It is generally supposed to come from the name of one Scheuster, a New York lawyer of that era who was constantly being rebuked by judges for his sharp practices. An alternative explanation, however, is that it represents an alteration of German scheisser, literally ‘shitter’.
"unscrupulous lawyer," 1843, U.S. slang, probably altered from German Scheisser "incompetent worthless person," from Scheisse "shit" (n.), from Old High German skizzan "to defecate" (see shit (v.)).