Green’s Dictionary of Slang

crooked dice.

1952		(con. 1920s) ‘Harry Grey’ Hoods (1953) 181: Max smiled and whispered [...] ‘Bust-outs,’ meaning that nine out of ten times a seven would show up.
1960, 1975		Wentworth & Flexner DAS.
1972		(con. 1950s) D. Goines Whoreson 100: Returning to the crooked dice, I made a few practice knocks with the bust-outs.