Green’s Dictionary of Slang

(US/W.I., Guyn.) to dress showily; thus stasher n., one who dresses ostentatiously, staching, ostentaious, fashionable.

1942		‘Digg Mee’ ‘Observation Post’ in N.Y. Age 29 Aug. 9/7-8: Stachin’ and drapin’ isn’t the same up on ‘sugar hill’ [...] [I] am sharp from toe to hat, a stachn’, booted, solid hepcat.
1996		Allsopp Dict. Carib. Eng. Usage 327/2: stash [...] To dress very showily [...] stasher [...] A woman who always dresses showily.