Green’s Dictionary of Slang

foolish, nonsensical.

1868		Sportsman 11 Mar. 2/1: Notes on News [...] Printer’s ink, and boshy [...] sort of verses.
1879		letter 9 Apr. in T. Hughes Gone To Texas (1884) 82: We don’t get too much literature out here to think letters are ‘boshy’; so scrawl away all you know.
1882		‘F. Anstey’ Vice Versa (1931) 62: There was no dancing, only boshy games and a conjurer.
1942		K. Williams Diaries 29 Jan. 2: Finished the litho map work — room for improvement. Levy to go to the RAF. Saw Citizen Kane — boshey rot.