Green’s Dictionary of Slang

(orig. US) a fool, an idiot, a boor.

1900		G. Burgess [bk title] Goops & How to Be Them.
1913		G. Burgess Goop Directory at www.popularchildrenstories.com 🌐 A Goop that always / makes me smile / Is this one: / Marmaduke Argyll.
1914		Sun (NY) 10 May 8/2: Another type of two-spot is the goop who is always shouldering around tell everybody he gave the house thunder for doing this or that.
1922		Washington Times (DC) 12 Nov. 32/6: You’d be surprised how lonesome a lot of goops get.
1934		Wodehouse Right Ho, Jeeves 14: The sort of shy, shrinking goop who might have been expected to shake like an aspen.
1939		J. Rhys Good Morning Midnight (1969) 133: Well, and what about it, you damned old goop?
1947		J.P. Marquand Polly Fulton 160: She was not afraid of such goons and goops. They amused her. They were simply ludicrous.
1953		J. Thompson Criminal (1993) 35: Bob stared at her like a big goop.
1970		E. Thompson Garden of Sand (1981) 34: What do you think about a hare-brained goop like that?
1989		Eble Campus Sl. Mar. 4: gooper – someone who is strange.
1989		H. Rawson Dict. of Invective (1991) 178: goop. A stupid, ill-mannered fellow.
2011		D. Telegraph (Sydney) 20 Dec. 🌐 I decided to create what I had been missing: the goop City Guide.