An Etymological Dictionary of the German Language/Schalk
Schalk, m., ‘rogue, knave,’ from MidHG. schalc, m., ‘servant, serf; person of servile character, espec. cunning person,’ OHG. scalch, m., ‘servant’; corresponding to Goth. skalks, OIc. skálkr, AS. sčealc, m., ‘retainer, man’ (so too the corresponding fem. sčylčen, ‘‘maid-servant’). The evolution in meaning is similar to that of AS. čyfes and wealh; see Kebse and welsch. Schalk passed at an early period into Ital., in which scalco signifies ‘head-cook.’ It is worthy of note that the meaning of the word is lifted into a higher plane in its transition from MidHG. to ModHG.; it is thus defined by Goethe, ‘one who plays a good-humoured practical joke.’