used to describe a promiscuous girl who likes to have sex in the back of a car. This is a rather old expression
two girls are jealous of a popular girl so they start a rumor that shes a "backseat betty".
A female who frequently has sex on the first date or first encounter.
Britney: Hey Lohan, did you call that guy we met at the coffee house yesterday?
Lohan: Yes, we met for drinks and well sex this morning.
Britney (laughing): Sometimes you can be such a back seat betty.
Nicole: Paris, did that guy give you a ride home from the club last night?
Paris(smiling): Yes, you could say that he gave me a ride last night.
Nicole: Your family should have been in the automobile business, because you are such a back seat betty.
Someone who frequently has sex on the first date or first encounter.
Jan's friends refer to her as back- seat betty
because of her many one night stands.
Chick who gets down and dirty and rides bitch on bikes.
I got all up in that backseat betty i took out last week.