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"