Green’s Dictionary of Slang

1. (Aus./US) a waiter or waitress.

1887		Bulletin (Sydney) 15 Oct. 12/1: In the absense of her parson-bestowed spouse she gradually evolved a partiality for chewing the radiant hasher’s eyebrow, and developed an undue fondness for the encirclement of her waist by his humerus, ulna and radius.
1905		Sporting Times 20 May 4/1: Scene the local ‘Hoffman House’ in Rossland B.C. And she was a new hasher.
1906		Sun (NY) 9 Sept. 3/2: I saw five or six St Regis hashers.
1913		(con. 1871) Jocknick Early Days on the Western Slope of Colorado 33: Mr. Trask did not at first grasp the idea that I was ‘it,’ — ‘the hashee;’ not until I had appropriated an apron.
1913–14		Van Loan ‘Easy Picking’ in Taking the Count 302: What he’ll do to this hasher will be plenty!
1927		W.R. Morse ‘Stanford Expressions’ in AS II:6 276: hasher—table waiter.
1932		J.A. Shidler ‘More Stanford Expressions’ in AS VII:6 437: The boy who hashes is called the ‘hasher’.
1948		N. Nye Breed of the Chaparral (1949) 21: The hasher came back in with his dinner.
1959		L. Caranco ‘Misc.’ in AS XXXIV No 1 78: hasher, n. A woman who waits on tables.
1992		N. MacLean A River Runs Through It 232: She’s a hasher down at the Greek’s joint.
1994		C. Hamlin ‘All Sewed Up’ in Weinberg et al. 100 Crooked Little Crime Stories 1: It began with Mamie working as a hasher in a Second Avenue joint, and Joe hanging over the counter, kidding her.

2. (US black) the mouth.

1940

Pittsburgh Courier (PA) 27 Apr. 7/6: You should stand pat at all times and keep your hasher closed.