Green’s Dictionary of Slang

1. brief, minimal.

1915		S. Ford Shorty McCabe on the Job 90: ‘Say, lemme tell you how it happened, won’t you?’ says she. ‘If it ain’t too long,’ says I. ‘I’ll make it sketchy.’.
1936		T. O’Reilly Tiger of the Legion 112: I am [...] used to ‘sleeping rough", but that was just a trifle too rough, and my sleep was of the sketchy variety.
1970		Honolulu Star-Bulletin (HI) 1 Jan. 28/2: Sketchy prison records from 1931 reveal [etc].

2. (US) second-rate.

1956		‘James Updyke’ [W.R. Burnett] It’s Always Four O’Clock 26: Remembering Royal’s reaction to Lonny Boyle, I shuddered to think how he’d react to Walt’s sketchy piano and Frank’s singing.
1995		Eble Campus Sl. Dec.
2001		‘Randy Everhard’ Tattoo of a Naked Lady 173: Sketchy motel, drug money, a homicide [...] Sounds perfect.
2020		C. Hiaasen Squeeze Me 137: Tortilla chips and a bowl of sketchy guacamole.

3. (US campus) confused, unstable, strange, unsettling.

1989		P. Munro Sl. U. 172: sketchy unsure, unstable, confused; jittery; strange.
1997–2000		College Sl. Research Project (Cal. State Poly. Uni., Pomona) 🌐 Sketchy 1. (adj.) [...] Usually used in reference to a male, who is presumed to be sleazy, although the details are unclear. [...] 3. Odd, abnormal, or strange.
1999		Eble Campus Sl. Nov. 11: [...] sketchy – weird, out of the ordinary.

4. (US campus) of people or objects, untrustworthy, suspicious.

1993		Eble Campus Sl. Apr. 5: sketchy – of questionable character.
2005		A. Swartz ‘Sweet, Tight and Hella Stupid’ in S.F. University High School Update Mar.–Apr. 2: sketchy – shady, of dubious moral quality.
2012		T. Piccirilli Last Kind Words 224: ‘See if his jacket has gotten sketchy in any way [...] If there’s been any kind of internal investigation into him. If he’s had a psych evaluation’.
2019		D. Winslow Border [ebook] If the guy feels sketchy, she’ll blow him with one hand on the [car] door handle.
2020		D. Winslow ‘Paradise’ in Broken 237: And it isn’t creepy [...] not at all dirty-old-man sketchy.
2023		(con. 1962) J. Ellroy Enchanters 152: [S]he couriers sketchy notes and bearer bonds for mogul types.

5. see sketch adj.