Green’s Dictionary of Slang

a term of general approval for anything favoured, e.g. a close friend, an item of clothing, a rock band, a given activity [note 19C use casual, not to be depended on, uncertain, ‘happy-go-lucky’; thus another e.g. of the bad = good model].

1981		Eble Campus Sl. Mar. 2: cazh – casual, laid back, socially optimal.
1989		P. Munro Sl. U. 54: Do you want to go to the movies tonight? — Okay, that’s cas.
1990		S. Morgan Homeboy 4: Nothing kasj about those brown and yellow stains.
1996		Eble Sl. and Sociability 36: All types of shortening are evident in college slang. The most frequent pattern of clipping is the loss of sounds from the ends of words: [...] cazh, from casual.
2002		‘Valley Girls’ on Paranoiafanzine 🌐 We’re the totally cas girls you see hanging out at the beach, the mall, and the 7-eleven.