Green’s Dictionary of Slang

lit. or fig., extremely unattractive.

1904		Sydney Sportsman (Surry Hills, NSW) 20 Apr. 1/1: Silent Sam will soon get like Plug Ugly Bill, better known than, respected.
1918		Nonpartisan Leader (Fargo ND) 22 Apr. 3/1: Abuse,, falsehoods and finally plug-ugly secret organization against the movement, marked its development.
1928		C. McKay Home to Harlem 61: That’s why when I wanted a man foh keeps I took me a black plug-ugly one.
1931		A. Bontemps God Sends Sun. 59: She called the plug-ugly girl to the door.
1940		S. Longstreet Decade 56: Old Jacob Astor may have been a plug-ugly fur thief.
a.1948		(con. early 1930s) C. McKay Harlem Glory (1990) 52: Keep your stinking mouth offa Charlotte, you plug-ugly mugger-fugger.
1962		(con. WWII) J.O. Killens And Then We Heard The Thunder (1964) 121: A great big blond-headed cracker, big and tall and plug-ugly.
1967		S. Hugill Sailortown 5: The scum of the earth, the scourings of the ports of the Seven Seas, plug-ugly deadbeats, lay-abouts, and [...] lousy sailormen.
1972		(con. 1916) G. Swarthout Tin Lizzie Troop (1978) 49: She may be the plug-ugliest woman I have ever met [...] but she is not going to play on my sympathy.
1997		Guardian 24 Oct. 45/1: ‘They’re all pug-ugly [...] I’ll show them who’s cool’.
1998		C. Fleming High Concept 79: A short, pudgy, plug-ugly woman.
2000		Guardian Weekend 15 Jan. 78: The more beautiful than average spend an hour a day; the plug-ugly give it less than a minute.