It is when a woman's breasts grow either very big or very fast.
Breast that grow big or fast; mammary denoting the human female breasts.
We can grow big breasts by doing sex with other boys because they suck our breasts.
Puberty causes breasts to grow fast to prepare you to have a child.
BIG
as big as God intends
Big.
As Big as E
Big breasts are 'des gros seins' (familiar/slangish) in French.
Genetics.
It varies!
A cup