A girl, usually a teen or young adult, that is still a virgin by choice. Some goodgirls have made out or gone to second maybe third but overall they rarely curse, are super respectful, kind, courteous, and usually intelligent. They want to try and wait until marriage to have sex or, at the very least, until they are in a committed relationship for a relatively long period of time.
Generally, these girls are hard to find but they do exist. :-)
Guy 1:I wanted to go all the way with this cute girl at the frat party but it turns out shes a goodgirl
Guy 2: damn dude what an old fashioned prude