Sometimes it's all in the eyes and lips IMO, I know for sure a look of girls use the old flirting with the eyes/lips as a tell tale sign..however I wouldn't say girls are as open about the matter as guys. I've heard my male friends ramble on countless times about how they 'really just want to bang her' or how they're 'stuck in the middle of a drought and need some', I can't say I've ever heard a sober girl say that.