Green’s Dictionary of Slang

1. (US) a moustache, thus nickname for someone who wears one.

1972		Pittsburgh Press (PA) 26 Nov. Roto 62/1: The Mustache Brigade [...] For the businesman there’s the Van Dyke or ’stache and goatee.
1973		Messenger (Madisonville, KY) 11 Aug. 1/2: ‘I’ve been a [ferris] wheel man for 15 years,’ ’Stache said. [...] ’Stache is short for ‘Mustache.’ His real name is Ken Dunaway.
1978		R. Price Ladies’ Man (1985) 103: His black Zapata ’stache looked phony, as if it were glued on.
2009		L. McIlvanney All the Colours 39: ‘Adam’s got a ’stache’.
2009		J. Stahl Pain Killers 18: The grin disconcerting [...] like rictus, with jowls and a cop ’stache.
2011		Ottowa Citizen (Ontario) 3 Dec. 19/1: Now it’s time to stash the ’stache. Or is it?
2017		L.A. Times 14 Jan. F11/3: I walways liked tedy Roosvelt’s scruffy salt-and-pepper ’stache.
2021		S.A. Crosby Razorblade Tears 157: He swung on Cockeyed while he kicked at Cat Stache.

2. see stash n.¹ (8)