shes the type of girl thats ok with being second best. or in my eyes the first place loser.
she waits around until you a your bf broke and takes the sloppy seconds.
more than likely has brown hair, chubby, and brown eyes.
she usually still keeps talking to your bf when you dont now it, because shes trying to get with him.
if you have a sleeze of a bf then he'll probably cheat on you with her.
2/3 of the time its a past ex, who wants another go.
you better watch out, your boy has all the symptoms of having a back up girl.
A girl who is only kept dangling by a guy whilst pursuing another, more attractive girl. Usually to have sex with when things go wrong.
My girlfriend was a "backup girl" before she met me.
"Are you dating her?"
"Nah man, she's just my backup girl."