A girl used on the sideline by a guy if he thinks his relationship is going to end, he will keep her there.
The guy will stay with his girlfriend usually and will keep another girl close to him while dating the other girl and the "friend" will be like a tease and when he gets dumped the tease will be his new girl.
The girl will be used as a "plan B" kinda thing.
Also known as USING.
Thomas: Yo! Brad what's with the new hot chick over there?
Eric: Nahhh man! Not what you're thinking.. she ain't my girl.. yet.
Thomas: Ohhh.. she your rebound girl eh?
A girl to fall back on for guys who just got dumped.
There are several girls in a class you can fall back onto after getting dumped, also called a rebound girl.