I don't like being referred to as a "girl" either! Especially in professional situations; I find it condescending. If I'm in the mood I'll make a point of asking how old these "girls" are when men refer to "this girl I work with" or "this chick from work". They do this, even if the woman is 50 and/or outranks them. Or I'll ask if they refer to their male colleagues as boys - never.