Green’s Dictionary of Slang

1. (US, mainly prison) a sidelong glance, usu. aggressive or unfriendly; also attrib.

1912		D. Lowrie My Life in Prison 148: This guy is altogether too fresh and keeps giving me the dog eye.
1924		G. Henderson Keys to Crookdom 403: Dog’s eye. Sidelong glance. Give him the dog eye – to glare at.
1931		Irwin Amer. Tramp and Und. Sl. 64: Dog Eye. – A close inspection or scrutiny.
1939		W. Winchell On Broadway 18 Nov. [synd. col.] Commissary day in prison [...] is also known as Dog eye day, Blackeye day and Sluggers day, because most prison murders occur that day.
1944		O. Ferguson ‘Vocabulary for Lakes, [etc.]’ AS XIX:2 106: The reproachful or supplicatory stare is the dog-eye or the moose-eye (‘And here is this big Korean dog-eyeing me all the time’).
1959		G. Duffy Warden’s Wife 63: After getting ‘dog-eye’ looks from their fellow-prisoners, they gradually abandon all pretences [i.e. of innocence].
1960		E. De Roo Big Rumble 24: Everybody gives the project manager the dog-eye.

2. (UK juv./Und.) a lookout, esp. for a team of three-card monte players.

1959		I. & P. Opie Lore and Lang. of Schoolchildren (1977) 400: In London districts the lookout functions under the names ‘ween-eye’, ‘dog-eye’, ‘dig-eye’.
1975		‘P.B. Yuill’ Hazell and the Three-card Trick (1977) 56: First off I spotted the dog-eye [...] You ever seen a man who can look in four directions at once? That’s a dog-eye.
1989		J. Morton Lowspeak.