A peanut; also slang for a silly or foolish person.
From Bantu language (Kikongo 'nguba'), brought through African diaspora to American English. The peanut meaning came from the food; the person meaning evolved from that as casual slang.
Goobers are a linguistic gift from African languages—English borrowed the Bantu word directly, making peanuts one of the few foods with an African-origin name in English. Mark Twain used 'goober' in his writing!
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