It depends what sort of "snob" you mean.
If she's an intellectually-lacking and highly superficial snob then just tell her she's fat/ugly/wears shit clothes.
If she's intelligent but very pretentious and snobby, then you'll want to insult her brains/wit/say something to imply that she, as a female, is a second-class citizen.
However, if she is the latter and she's anything like me, you probably won't get away with it.
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Actually, you should even be careful with the dumb snobs, because they can be vicious creatures too.