Green’s Dictionary of Slang

1. (US, also goony) a fool, an idiot.

1904		G.D. Chase ‘Cape Cod Dialect’ in DN II:vi 425: gooney, n. A stupid fellow. ‘You great gooney, don’t you know anything?’.
1909		G.D. Chase ‘Cape Cod Dialect – Addenda’ in DN III:v 420: goony, n. A stupid person.
1935		A.J. Pollock Und. Speaks 47/1: Gooney, a chump; boob.
1985		Goonies [film title].

2. (US, also gooner, goonie) a foreigner, an enemy, esp. a Chinese communist soldier; also attrib.

1944		P. Kendall Dict. Service Sl. n.p.: gooney gals . . . young native girls.
1958		(con. 1950) E. Frankel Band of Brothers 4: If I was a goonie, you’d be buzzard bait by now.
1968		B. Adler Vietnam Letters (2003) 3 Feb. 64: I shot it at the corner of Bunker 2, blowing my gooney friend into Valhalla or wherever dead gooks go.
1978		J. Webb Fields of Fire (1980) 12: More gooners than I ever seen. We could really be in the hurt locker tonight.

3. (Aus.) cheap, cask wine.

2007

D. McDonald Luck in the Greater West (2008) 5: Pete the Bull poured Fruity Lexia [...] ‘Want some gooney, Whitey?’.