Green’s Dictionary of Slang

con adj.

[con n.1 (6)]

pertaining to confidence trickery or confidence tricksters; in a weak sense, deceitful.

[US]Ade Artie (1963) 83: I’d been readin’ them con story-books about pickin’ flowers and goin’ fishin’ and dubbin’ around the woods.
[US]C. M’Govern Sarjint Larry an’ Frinds 133: ‘Con’ stories wot soldiers pass along to each other just by way of killin’ time.
[US]Perrysburg Jrnl (Wood Co., OH) 22 May 2/1: It’s put this con life of our on the fritz, for fair!
[UK]E. Jervis 25 Years in Six Prisons 56: My ‘con’ friends have said to me [...] ‘We soon get to know each other out there, and are ready for any game.’.
[UK]J. Curtis Gilt Kid 20: Come on guy for a con gang, ain’t you?
[US]Kerouac letter 17 May in Charters II (1999) 35: W. C. Williams is sore about a big con letter Gregory wrote from Paris.
[UK]R. Cook Crust on its Uppers 51: I wasn’t quite certain whether the whole thing was a giant con trick.
[US]L. Pettiway Workin’ It 109: I knew the basics of this con thing.