Girlfriends Annoying sister?

Has anyone ever had a girlfriend who's sister was annoying and disrespectful as **** . For example my girlfriend is a quiet type and her sister is this loud mouth attention seeking gold digging ***** for example her one boyfriend which only lasted like 3 weeks (this doesnt suprise me) bought her a $300 Iphone and then she breaks up with him for some stupid reason like he wants to care for her to much or he tells me he loves me to much or some dumb **** like that. Then she just keeps the phone like nothing happend. She is constantly one her cell phone talking to all these men telling them ooo your so y all this **** and she has to say EVERYTHING out loud so EVERYBODY can hear her conversation .She for real constantly hangs out with men just for attention. She has to ALWAYS wear these hoochie tight clothes that just has to show her clevage all the time and everythime i see her she always just has to say something really ignorant about stuff and its REALLY ANNOYING..And like i said before she always has to say something mean about me or something i just think she is jealous because i have been with my girlfriend for like 4 years and over that 4 yr period her sister has had like 10 diffrent boyfriends and i think she is just jealous of my girlfriend me and me or something. So does anyone have any advice or expirienced this as well.