A girl who's vaginal opening has been stretched and mangled beyond functionality. Various nerves have been destroyed due to rapid and frequent contact with bulbous peni.
Implying that an item (or person) is ruined, bad or nasty. It can include but is not limited to having a loose vaginal cavity, bad overall personal hygiene, or even habits that would deem someone as lower social status.
Kim is blown out because she drinkstoo much and mistreats her kid, and slept with Casey right after she met him.