Green’s Dictionary of Slang

sheisty adj.

also shiesty, shisty
[shit adj. (1)/shicer n. + feisty adj.]

(US black/campus) underhand, unethical, untrustworthy, criminal.

[US]Dr Dre ‘Deep Cover’ [lyrics] Take a strap just in case one of his boys recognise my face. / Cause he’s a shisty motherfucker.
K. Beck on Urban Dict. [Internet] shiesty when a person is acting shadey...kinda I guess talking smack behind ur back... then acting like everythings peachy king when youre face to face with them. Man, youre shiesty!
[US]College Sl. Research Project (Cal. State Poly. Uni., Pomona) [Internet] Shiesty (adj.) 1. Slick, sly, or devious. [...] 2. Nasty, scummy.
[US]W. Shaw Westsiders 273: I’ll be the sheistiest motherfucker to my family, he says to himself.
[US]Times (Shreveport, LA) 2 Aug. 9/1: The industry is shady. Seedy. Sheisty.
Hartford Courant (CT) 24 July PE04/4: It’not that we think they’re sheisty or are trying to pull a fast one one us.