Aptly stands for 'Super Tan Girl'; a combination of a Gina and Valley Girl into
one entity. Usually blonde, but is based on the overexcessive and obvious fake
bake the girl has undergone.
Also associated with the more
popular crowd, but not necessarily meaning that they are.
"Do you
think that she went on
vacation?"
"No, she's just an STG"
or
"That girl over there is such an STG"
"tell me about it, she could
support the whole bronzing industry single-handedly"