Green’s Dictionary of Slang

a complaint; thus grouser, a complainer.

1885		B. Patterson Life in the Ranks 120: This select and volatile body of men is commonly designated by their more sensible and forbearing comrades as the ‘grousers’ from the fact that the chief elements of their composition seems to be made out of grumbling.
1918		Aussie (France) 4 Apr. 4/2: The regimental grouser had been talking incessantly for five miles.
1925		A. Christie Secret of Chimneys (1956) 189: You are an old grouser.
1933		Horsham Times (Vic.) 23 June 10/6: It’s just a grouse, a silly unthinking, and illogical grouse.
1940		Sun. Times (Perth) 4 Feb. 9/6: [heading] Digger’s Grouse.
c.1943		‘Bill O. Lading’ You Chirped a Chinful!! n.p.: Grouse Me: Chronic grumbler.
1955		Picture Post 23 July 7: Readers’ letters printed and answered in this column will earn a guinea for the sender. Mark your envelopes GROUSERS’ CORNER.
1956		J. Curtis Look Long Upon a Monkey 67: He was the Orderly Sarn’t passing on a legitimate grouse, putting it in simple words even the officer’s dim wits could grasp.
1964		P. White Burnt Ones 312: He could tell a grouse was coming.
1974		G.F. Newman You Flash Bastard 110: DS Watson bought Sneed a drink, and Sneed listened to a few of his grouses; the pub was where they usually came out.
2003		Grosvenor & Burke School I’d Like 28: Our school is made from a big old house, / About some things we have a grouse.