Slang for Saginaw, Michigan
Hey, I know that dude! He from Sag-Nasty!
Sag-Nasty is the nickname for the post-industrial, mid-Michigan rust-bucket town of Saginaw.
It is also an apt description of the breasts of a female rapper named Khia.
Why doesn't Khia wear a bra? Surely she knows that her boobs Sag-Nasty.