NOUN: A girl that is willing to be treated like a doormat or booty call. She is a girl that will allow guys to do whatever they want with her and will just wait for them to 'holla back' at them.
VERB: a member of a cheerleading squad who repeats – hollers back - words that the squad leader shouts out to them.
Gwen Stefani uses the term brilliantly in her song "Hollaback Girl", both as a simile and a metaphor. She’s letting the guys know that she ain’t a booty call and that she’s not gonna be sitting around waiting for them to “holla back”. She’s “been around the track a few times” so it’s not gonna happen again. She uses the cheerleading terminology as a metaphor, she’s a “squad” leader not a follower.