Green’s Dictionary of Slang

(US) a Czech immigrant.

1920		T. ?apek ?echs in America 114: In some localities Bohemians are called ‘Bohoes’, in others ‘Bohunks’; less familiar are the terms ‘Cheskey’ and ‘Bootchkey’ .
1936		Mencken Amer. Lang. (4th edn) 295: For Czech: bohoe, bohick, bohee, bohunk, bootchkey and cheskey.
1986		Chapman NDAS 36/2: boho n. [...] An immigrant from central or eastern Europe, usu a Czech, Slovak.