Green’s Dictionary of Slang

1. a Portuguese [joc. pron.].

1853		Life in Boston & N.Y. (Boston, MA) 1 Oct. n.p.: A certain Pork and Beans is notified that we have enclosed a bill for $2 [...] which we wish to have settled.
1921		N&Q 12 Ser. IX 458: In a very short time the expression ‘Pork and beans’ to denote the Portuguese achieved such success that the powers that be, fearing it might be regarded as an insult, issued a stringent order [...] that it and similar expressions were not to be used.
1925		(con. WWI) in Fraser & Gibbons Soldier and Sailor Words.
1930		(con. 1914–18) Brophy & Partridge Songs and Sl. of the British Soldier.
2002		(ref. 1940s) B. Morrison Things My Mother Never Told Me 86: I’d not heard of the Portugese being Pork ’n’ Beans.

2. (US black) a means of living, one’s livelihood.

1960

(con. 1940s) I. Freeman Out of the Burning (1961) 29: That bike is our pork and beans; ain’t no toy.