Green’s Dictionary of Slang

1. (US) a Lithuanian or person of Lithuanian background.

1947		W. Motley Knock on Any Door 110: Inside a bunch of the neighborhood men, polacks and lugans and a big Russian with an accordion, got together week ends.
1964		in PADS [DARE].
1969		in DARE.
1995		in DARE.

2. in a canival use, the most easily exploitable of victims.

2012

W. Keyser ‘Carny Lingo’ in http://goodmagic.com 🌐 Lugen — An unbelievably dumb, easy mark.