A chub nigga can be known by the kid who's name is like "Chuck". The chub ass "Chuck" child tried to nig around but can't do anything for his life.
The Chub Nigga can often be the weird ass kid who tries to fit in, but does not. You will know one one you see one, they give off that vibe.
Something you'd call someone who is small. Sometimes it is used as a term of endearment but it also can be used as an insult or a way to make fun of a short person. The person being called Chibi Chan is in denial about being shortmost of the time.
Tall person : Hey, Chibi Chan!
Short person : Stop calling me that, loser!!
Tall person : But I want nothing but to love and support you! You repay me by calling me names?
Short person : Whatever. Go away!
The child version of N.Italy in a series called Axis powers: Hetalia. He works in Austria's house as a maid. He was mistaken for a girl by many other characters since he was often wearing girl clothing because of Hungary dressing him up. This resulted in the Holy Roman Empire (HRE) to fall in love with him.
Chobi is derived from the popular Manga/Anime "Chobits". In the series, Ichiro Mihara used the word "Chobi" to describe anything that he thought was small and hopelessly adorable.