Green’s Dictionary of Slang

(US) a fat person.

1971		T.C. Bambara ‘My Man Bovanne’ in Gorilla, My Love (1972) 8: She was a chub-chub like me and not very pretty.
1981		Eble Campus Sl. Fall 2: chubo-twin – a person who thinks she is overweight: When my roommate gains even five pounds, she calls herself a chubo-twin.
2002		Tracy’s Homepage 🌐 I was a cute little chubbo, wasn’t I?