I guess the thing is though that they want to look sexy, and try to have guys notice their bodies (at least from a guy’s perspective)
Hmmm… having read through this thread, I don’t think it’s possible to give you a useful answer without some context. Do you go to a Catholic college/university? Are your friends Catholic? (I would assume so, if you’re referring to your admiration for Padre Pio…)
If your friends are not Catholic, or are not well-catechized, they may not have much of an idea of what modesty
is, let alone value it. If this is the case, I would think that harshly admonishing them would accomplish nothing good, only convince them that you’re not a very nice person.
If you’ll give a hearing to the perspective of a woman considerably older than yourself, (and somone else has pointed this out, too) most normal women do not actually
want to be objectified by men, however much their clothing might scream that they do.
Women who are not Catholic, or who have not been well catechized, have been taught-- at the feet of the popular media and the fashion industry and by the example of those around them (men as well as women, sorry)-- that men are attracted to “sexy” women and the way to catch the attention of any eligible men is to choose clothing that flaunt their bodies.
What these young ladies want is to garner attention from young gentlemen like yourself- the immodest clothing (in their minds) is simply a means to that end. Thus, telling them “that’s immodest” or “you should put some more clothes on” is going to seem a) beside the point and b) mean to them, so I would try to put more gently.
If you want to teach them a little bit about modesty, it would be wise not merely to admonish them when they wear immodest clothing, but complement when they wear clothes that are not revealing- or if not friends, find a modestly dressed woman in the room to speak positively about.
(Although, as an aside, I cannot understand your friends anyway. I would have had all my toenails forcibly removed as an undergraduate, before I asked some guy (no matter how good a friend he was) what he thought of my dress, much less ask repeatedly.)