look up any word, like doxx:
 
1.
A girl who has absolutely no potential to be your long-term girlfriend but you want to stick it to anyway.

See: Future ex-girlfriend
Guy 1: Bro, i can't wait to hang out with you and my FXGF tomorrow.

Guy 2: Stop talking about my sister that way, asshole.
by Your FXBF November 08, 2012