An ex-girlfriend that has "turned gay" after a break up with her boyfriend. It is often considered cool for a guy to have one ex girlfriend who is now lesbian, however more than one in a man's past indicates a problem with him.
John: "Do you think that you and Jane will ever get back together?"
Chris: "Nah man, she went all exbian on me."
Michelle: "Girl, don't go out with that guy, he's got like five exbians..."
Lisa "Whew, thanks for the tip. I don't wanna catch that."