Me and my gf have a really close guy friend. All 3 of us would sometime hang out at my gf's place. What happen is that my gf has a tendency to wear very little when she is at home. Little as in just a dress like this*linkremoved* over barely covering her bum with nothing under. Nothing as in no bra and pantie. So basically she was wearing like that even when he's here. What do I say to her to avoid her having these kinds of moment again? How can I stop it?