Puerto Rican Pendleton, n. — Green’s Dictionary of Slang

Puerto Rican Pendleton n.

[derog. ref. to the poverty of Puerto Rican labourers, for whom an expensive Pendleton shirt would be an impossible dream]

(US) an old workshirt.

1979

Maledicta III:2 171: Puerto Rico Pendleton n Old work shirt; so called because ‘Pendleton’ is a shirt manufacturer, and because of the stereotype of the poor Puerto Rican laborer.