SHY*STER:
Probably alteration of German Scheisser, son of a bitch, bastard, from scheissen, to defecate, from Middle High German schzen, from Old High German skzzan. See skei- in Appendix I

WORD HISTORY:
Calling someone a shyster might be considered libellous; knowing its probable origin adds insult to injury. According to Gerald L. Cohen, a student of the word, shyster is derived from the German term scheisser, meaning literally “one who defecates,” from the verb scheissen, “to defecate,” with the English suffix –ster, “one who does,” substituted for the German suffix –er, meaning the same thing. Sheisser, which is chiefly a pejorative term, is the German equivalent of our English terms bastard and son of a bitch. Sheisser is generally thought to have been borrowed directly into English as the word shicer, which, among other things, is an Australian English term for an unproductive mine or claim, a sense that is also recorded for the word shyster.

http://en.wikipedia.org/wiki/Shyster