Green’s Dictionary of Slang

(US) basic, unenterprising.

1882		E. Nye Forty Liars (1888) 24: Every pork-and-beans pilgrim [...] has said that the miner slings more unnecessary professional racket than anybody else.
1915		Van Loan ‘Sporting Doctor’ in Taking the Count 20: That was the beginning of Phelps’ pork-and-bean practice, as he called it [...] ‘The Doc is all right,’ said the pork-and-bean fighters.
1923		H.C. Witwer Fighting Blood 122: I got to try my luck at something, unless I want to wind up as a pork-and-bean pug.
1931		W. Noble Burns One-Way Ride 35: Piggy Joyce, once a pork-and-beans grifter, thought nothing of losing or winning $50,000 a night.
1936		K. Mackenzie Living Rough 33: The way you swum from that beach you’d have made Johnny Weismuller look like some pork-and-bean amateur.
1956		‘Ed Lacy’ Men from the Boys (1967) 39: He came out of the army a pork-and-bean middleweight, but smart enough to give up the ring.