Grellmann (1787) collected the forms Shukkerben ‘Beauty’ and Schoker ‘Reʃpectable’ from Continental gipsies. However, another possible connection from Grellmann is schukrohilo from Continental gipsies which he thinks derives from Hinidi sukka ‘dry’. So a shukar kip is a dry bed.
Smart & Crofton (1875) collected a form Shookár adv., ‘nicely, quietly, slowly, easy’ from English Gypsies.