Green’s Dictionary of Slang

barney n.3

1. (US campus) an unsophisticated person, one who is not part of currently approved fashions or attitudes [mid-19C: ? negative stereotyping of Irish immigrants; 1980s+ plays on the proper name Barney Rubble, a character in the TV cartoon (and latterly the film) The Flintstones].

[US]Ely’s Hawk and Buzzard (N.Y.) 21 June 1/1: An independent loafer can be accommodated with a bonk [sic] or rat hole to crawl in for eight pence — a loafer of some distinction, one for six pence — a Barney of little quality four pence.
[Scot]Dundee Eve. Teleg. 28 Dec. 4/5: ‘Barny’s’ Visit to Forfar [...] Bernard M’Kay, a labourer of no fixed resience, admitted a charge of [...] drunk and incapable.
[US]S.J. Perelman letter 6 May in Crowther Don’t Tread on Me (1987) 3: A flock of dumber barnies than the clerks at the Sub-Treasury I never met.
[US]P. Munro Sl. U.
[US]A. Heckerling Clueless [film script] I don’t know where she meets these Barnies.
[US]Eble Campus Sl. Spring 1: barney – someone clumsy or uncouth: ‘He plays computer games all day – what a barney!’.

2. (US campus) an attractive man [? f. sense 2; or ? Barney’s, the fashionable New York department store].

Online Sl. Dict. 🌐 Barney n 1. an unattractive male. (‘He is such a Barney’).