Green’s Dictionary of Slang

chupid adj.

(W.I.) gullible, ignorant.

1869		H.G. Murray ‘Tom Kittle’s Wake’ in D’Costa & Lalla Voices in Exile (1989) 91: Cho, go ’bout you business, man; you is chupid boy.
1896		in Journal of Amer. Folklore Apr. IX 32: It da jump about, and shake him head, and do all kin’ o’ ’tupid ting.
1902		J. Speirs Proverbs of British Guiana 13: Chupit man gie ’way he ’poon, an’ eat wif’e han’.
1922		A. Gonzales Black Border 293: chupid / chupit – stupid.
1978		W. Redhead Three Comic Sketches 8: Is only a chupidee man what doesen’t listen to he wife.
2004		A. Khan Calalloo Nation 171: He also must negotiate a fine line between accommodating simplicity and not insulting participants by implying that they are chupidee— ignorant, stupid.

In derivatives

chupidness (n.) (also trupidness)

gullibility, foolishness, nonsense.

1983		R. Abrahams Man-of-Words in the West Indies 96: He is classed as a fool and accused of talking trupidness. [...] Talking trupidness is expected [...] from persons who really are trupidy.
1988		W. Chen King of the Carnival 155: Chupidness: stupidity.
2006		W. Chen Chutney Power and Stories 33: Her neighbours always laughed loudly at ‘chupidness’.