The term was introduced from the movie "Mean Girls". Usualy mistaken for the term "material girl" because they dress well - but not for themselves but more so to impress and make a statement! It's usually an insult refered to girls who are way over there heads, put themselves first, plain heartless and just plain fake! They put on make up everyday and look ugly without it. They put on lipgloss every few seconds. They'll be the ones starting drama in school and minipulating all the boys. It's not hard to spot one, just don't be fooled by their charm. They're called plastic for a reason, that's because they don't feel anything and any insults you run by them will slip off just like cold shiny plastic!
Jock 1: Sweet Lord!! Who is that fine new lady?
Jock 2: Careful man, she's cold plastic... Don't date her, you don't want no drama!
Girl 1: Wow she's goregous!! I wanna be like her!!
Girl 2: She may be gorgous... But minus the make-up, hair, and her trampy clothes... She's a souless plastic!
Girl 1: Eckkkk... That's too shallow for me!