A girl (or in some cases boy) who is destined to one day be a whore, she may be "naive" and silly, but she possesses characteristics of someone who will one day make an excellent candidate for a whore.
"Wow, she snuck into a...boy's...hotel room, she is such a babywhore." or "Wow, did you sniff her perfume, Paris Hitlon's new scent, yep, total babywhore." "Wow, a little revealing shirt you have on there, huh? Baby whore.