gas-house mick, n. — Green’s Dictionary of Slang

gas-house mick n.

[they live near the original gas-houses that lined New York’s East River between 14th Street and 22nd Street. The first gas-house appeared in 1842 and its peers followed over the next 50 years; the orig. Gas-house district covered 3rd Avenue to the river and 14th Street to 27th Street. The smell of leaking gas and the poor neighbourhood housing meant that few lived there by choice, but among those who did were the feared thugs of the Gas-house gangs]

(US) a poor or lower-class Irish person.

[1912		Van Loan ‘Sweeney to Sanguinetti to Schultz’ in Ten-Thousand-Dollar Arm 47: Sweeney [...] came from the gas-house district of a great city].
1929		W.R. Burnett Little Caesar (1932) 102: You act like a bunch of gashouse micks.
1930		W.R. Burnett Iron Man 104: He don’t look clever to me [...] He just looks like a little gas-house mick.