South Los Angeles term used to describe something, (usually an article of clothing) that fits and looks too small on a person.
It's not exclusive to articles of clothing. It can apply and be used to describe anything that is too small.
Did you see that baby mini tee shirt that fool had on?
Her grill is busted with those baby mini troll teeth.
If he wears those baby mini skinny jeans one more time, I swear.
He ain't got no money, with his baby mini bank account.
That big ass girl knows she doesn't need to be riding that baby mini bike with her big ass.