Green’s Dictionary of Slang

(US) an old Polish immigrant.

1942		N. Algren Never Come Morning (1988) 87: ‘Jesus Kelly Christ! [...] I ain’t gonna stay in here! Hey! You! Boobatch!’ Bruno Bicek knew no better word to indicate a church-going, foreign-born Pole than ‘boobatch’. The boobatch made no reply.
1947		N. Algren Neon Wilderness (1986) 75: We seen this boobatch with his collar turned inside out cash’n his check by Konstanty Stachula’s Tonsorial Palace of Art.
1974		(con. late 1940s) E. Thompson Tattoo (1977) 486: He saw himself a crablike old boobatch scuttling between skid row bars, flashing his tattered discharge papers in pursuit of a drink.