Green’s Dictionary of Slang

primo adj.

[Sp. primo, first]

first-rate, excellent; usu. referring to the quality of a drug; also as excl. (see cite 2010).

[US]Atlantic Monthly Jan. 10/2: Who’s buying the primo stuff [i.e. marijuana]? None of my people can touch it – it goes for $120 to $200 an ounce.
[US]J. Ellroy Brown’s Requiem 44: The courses round here are the primo land in L.A., worth billions of bucks.
[US]M. Leyner Et Tu, Babe (1993) 76: Sure the lincoln’s morning breath had been primo shit.
[US]R. Shell Iced 136: Dalek [...] pulled out a pouch of some primo-reefer.
[US]G.A. Haywood ‘And Pray Nobody Sees You’ in Woods Spooks, Spies and Private Eyes (1996) 185: Orange ’65 Mustang in primo condition.
[US]E. Weiner Drop Dead, My Lovely (2005) 45: I’m whack on contracts but do primo litigation.
[Aus]L. Redhead Peepshow [ebook] Primo shit [i.e. cocaine]. You can’t get this on the street.
[Scot]T. Black Gutted 253: I pointed the way through the winding streets, littered with deros, trash and more than a few needles [...] ‘No exactly primo real estate’.
[US]L. Berney Gutshot Straight [ebook] ‘Primo!’ Rock Star said, bouncing around with delight and relief.
[US]D. Winslow The Force [ebook] It’s primo shit [...] A sweet, mellow high.