Marge: You meet the worst kind of guys when you're on the rebound. That's how Jackie got her O.
Marge seems to be referring to Jacqueline Kennedy, who some years after the death of her husband president John F. Kennedy married Aristotle Onassis, a Greek shipping tycoon. Afterward she was sometimes referred to as Jackie O. By the way, Jackie O's maiden name was Bouvier, the same as Marge.