Green’s Dictionary of Slang

1. a person with a round or blank face, a stupid person; a term of abuse.

1896		Ade Artie (1963) 74: Who is the main guy up at your place—the pie-face I spoke to the day I come up to see you?
1906		Eve. World (NY) 6 Jan. 8/2: This pie-face says that ten of our boys were sent down there to wait for the ransom.
1915		J. London Star Rover (1963) 36: Pie-Face Jones was a mean and bitter man, despite his fatness.
1928		D. Lawley Hustling Hobo 77: The boys smiled and chaffed, but none dare to refer to the lady known as Pie Face.
1930		W.S. Maugham Bread-Winner Act I: Come along, young pie-face.
1949		R. Park Poor Man’s Orange 33: ‘Hullo, fishface,’ she chirped. ‘Hullo, pieface,’ returned Dolour unsmilingly.
1965		A. Lurie Nowhere City 23: I’m pissed off at you, pie-face.
1974		J. McNeil How Does Your Garden Grow Act II: Aw, come on, pie-face.
1982		Beano 17 Apr. 1: Couldn’t let pie-face see me!
1990		Dennis the Menace Annual 18: Come here, Pie-face.
2002		I.F. Ferris A Few Good Women 38: Hi Pieface, what did you bring me today?

2. (Aus.) an Asian [the cuts in a pie-crust that supposedly resemble slanted Asian eyes].

1985

National Times (Aus.) 26 Apr. 26: It was not enough to stop him shouting ‘There’s pie-face in ther audience!’ when he spotted an Asian sitting in the front row [...] Jackson told The National Times later that pie-face was a nickname for Asians, because pies had litle marks in the top of them like ‘slant eyes.’ [GAW4].