Green’s Dictionary of Slang

crazy, eccentric.

1953		L. Uris Battle Cry (1964) 53: You can take tanks [...] and any other goof ball invention and jam it.
1962		K. Orvis Damned and Destroyed 39: You talk a lot. In fact, you’re the granddaddy of all goofball windbags.
1980		A. Maupin More Tales of the City (1984) 203: It’s just plain goofball [...] Why would a cathedral make anybody have amnesia.
1999		Observer Screen 25 July 5: Now he’s back [...] playing a goofball cop.
2002		D.H. Sterry Chicken (2003) 82: Eyes bugging and arms stiff, a goofball kid criminal being hanged to death.
2005		L. Theroux Call of the Weird (2006) 35: They’re all a bunch of goofball jerks.
2010		A. Steinberg Running the Books 86: Yoni’s goofball antics - blowing a lewd kiss and winking into the camera.