Green’s Dictionary of Slang

chile n.

a derog. term for a Mexican.

1936		R.F. Adams Cowboy Lingo 198: To the cowboy a Mexican was a ‘greaser,’ [...] ‘chili,’ ‘chili-eater,’ or ‘bean-eater’.
1943		W.R. Burnett Nobody Lives for Ever 129: He wanted to dress up in his best and swell around the hotel [...] and take a gander at the upper-class chilis.
1978		Maledicta II:1+2 (Summer/Winter) 154: Chile Bean See Bean.
1980		E. Folb Runnin’ Down Some Lines 232: chili bean See bato.
1983		Maledicta VII 24: One of the peppers, of course, is chili, and Mexicans have also been dubbed chili, chili bean [...] and an alliterative chili chomper.
1989		H. Rawson Dict. of Invective (1991) 228: Chili or chili eater, a Mexican (members of the Border Patrol are sometimes known as chili chasers).

In phrases

get one’s chili up (v.) [var. on get one’s Indian up under Indian n.]

(US) to be infuriated.

1966

‘Tom Pendleton’ Iron Orchard (1967) 211: Ort, I believe you got your chili up, pardner.