Green’s Dictionary of Slang

commissary department n.

also commissariat department, ...region
[SE commissary department, in milit. use the department that deals with the buying, preparing and distribution of food]

(US) the stomach.

[US]Wichita Weekly Beacon in Rosa & Koop Rowdy Joe Lowe (1989) 75: A derringer was held against his commissary department and snapped.
[US](con. 1875) F.T. Bullen Cruise of the ‘Cachalot’ 78: Being unable [...] to masticate his food, [the whale] was compelled to tear it in sizable pieces, bolt it whole, and leave his commissariat department to do the rest.
[Aus]Bulletin (Sydney) 8 Nov. 14/4: The ‘fine woman,’ however, is foolish to divert her abundance [i.e. breasts] to – of all places in the world – the commissariat region!
[Aus]Bulletin (Sydney) 19 Nov. 36/2: A piece of springy timber has struck Mr. Swallow-tail in the commissariat department.