Green’s Dictionary of Slang

(US Und.) a robbery that takes place while the occupants of a house are gathered together eating; thus supper man, supper sneak, one who carries out such a robbery.

1879		Nat. Police Gaz. (NY) 20 Dec. 11/3: ‘Supper sneaks,’ or thieves who work dwellings while the family are at tea.
1882		Rock Is. Argus (IL) 24 Mar. 2/3: These gentlemen are classified as bankrobbers, cracksmen, gophermen, night workers, climbers [and] supper sneaks.
1908		‘O. Henry’ ‘From Each According to his Ability’ in Voice of the City (1915) 221: Pickpocket, supper man, second-story man, [...] and slickest con man west of the Twenty-third Street ferry landing.
1926		J. Black You Can’t Win (2000) 120: This is about the time of the year for a good ‘supper sneak’; it’s dark when they are at dinner.
1952		C. Hamilton Men of the Und. 325: Supper sneak, A robbery of the second-story of a house while the residents are at supper.