Green’s Dictionary of Slang

slope n.2

also slopehead, slopie, slopy
[the supposed ‘slope’ of East Asian eyes]

1. a derog. term for an East Asian person, esp. Vietnamese, Korean.

[US]J.L. Riordan ‘A.V.G. Lingo’ in AS XXIII:1 30: Life among our little brown brothers—who were sometimes less affectionately referred to as slopies, coosies, or flange-heads—was much different from that among the Wogs in India.
A.A. Weinstein Barbed Wire Surgeon 270: ‘Sergeant Aria [...] these men, as you know, have beri-beri heart disease.’ ‘Yes, yes,’ the slopehead said.
[US](con. 1950) E. Frankel Band of Brothers 4: You seen any slopeheads?
Richard McKenna Sand Pebbles n.p.: ‘They’ll run,’ Crosley said. ‘Slopeheads always run.’.
[US]Army Reporter Feb. in Maledicta VI:1+2 251: I know you numbah fuckin’ ten cheap charlie, so di-fucking-mau, slopehead, and never come this way again.
[US]T. O’Brien Going After Cacciato (1980) 9: A letter [...] that described Japan as smoky and full of slopes.
[US]J. Wambaugh Glitter Dome (1982) 168: He just might be telling the truth about not knowing the slope too well.
[Aus]B. Humphries Traveller’s Tool 60: A nice little slopie who had luckily been waiting outside this joint all night.
[Aus]C. Bowles G’DAY 92: Ockers are worried that the slant-eyes, slopeheads, wogs and other reffos are going to take over the joint.
[US]‘Joe Bob Briggs’ Joe Bob Goes to the Drive-In 144: Had to pay this Turkish slopehead 18 bucks to get the thing in one of those crates.
[US]W.T. Vollmann Whores for Gloria 36: Fighting the fucking gooks and slants and slopes.
[US]Tarantino & Avery Pulp Fiction [film script] 68: He’d be damned if any slopeheads were gonna put their greasy yella hands on his boy’s birthright.
[UK]J.J. Connolly Layer Cake 95: I can hear Hugo ranting about giving Hong Kong back to the slopeheads.
[US](con. 1964–8) J. Ellroy Cold Six Thousand 342: What kind of reading can you get off little slopes like that?
[US]G. Pelecanos Way Home (2009) 204: The Jews and the slopes who we were robbin, they knew we meant business.
[US](con. 1968) P.L. Nelson Incessant Voice of War 3: To him, all orientals are the same. Slopes, Gooks, Zips.
[UK]Guardian 28 July [Internet] Ofcom says BBC breached broadcasting rules when it allowed presenter to use word ‘slope’ about Asian man.

2. attrib. use of sense 1.

[US](con. 1950) E. Frankel Band of Brothers 113: Cost us a slopehead flag and two months’ coke rations.

3. used for any foreigner, not necessarily Asian.

[US]‘Joe Bob Briggs’ Joe Bob Goes to the Drive-In 126: Some people don’t have the decency and respect for human life that make us different from the slopeheads in Communist Russia.

SE in slang uses

In phrases

slope in a cup with the light out (n.)

(US short order) black coffee.

[US] ‘Dict. of Diningroom Sl.’ in Brooklyn Daily Eagle 3 July 13: ‘Slope in a cup with the light out’ signif[ies] coffee without milk.