Green’s Dictionary of Slang

slope adj.

also slopehead, slopie
[slope n.2 (1)]

(US) East Asian, esp. Vietnamese.

[UK](con. 1944) A. Myrer Big War 288: Peering down at one of the Japanese [...] ‘Never thought you’d wind up starched like this, did you slope-head son of a bitch?’ he said.
[US](con. early 1950s) J. Peacock Valhalla 116: His slope-head scissor-cut under a bowl. [Ibid.] 169: Goddam slopehead gooks.
[US](con. 1969) M. Herr Dispatches 138: Ain’t a Slope bitch in this whole fucked-up country that loves it.
[US]H. Crews Feast of Snakes 25: I didn’t have no more sense than to step on a stick with slopehead shit all over it.
[Aus]B. Humphries Traveller’s Tool 37: My best suits […] are made by slopie craftsmen.
[US]W.T. Vollmann Whores for Gloria 137: Slope food!
[US]G. Pelecanos Night Gardener 268: ‘Go over to that slope-house and get a steak and cheese.’ [...] ‘How you so stupid? You don’t never buy a sub from a place got chinese food.’.